Vulnerable Library - express-4.21.2.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Vulnerabilities
*For some transitive vulnerabilities, there is no version of direct dependency with a fix. Check the "Details" section below to see if there is a version of transitive dependency where vulnerability is fixed.
**In some cases, Remediation PR cannot be created automatically for a vulnerability despite the availability of remediation
Details
CVE-2026-4867
Vulnerable Library - path-to-regexp-0.1.12.tgz
Express style path to RegExp utility
Library home page: https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.12.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/path-to-regexp/package.json
Dependency Hierarchy:
- express-4.21.2.tgz (Root Library)
- ❌ path-to-regexp-0.1.12.tgz (Vulnerable Library)
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
opentok-sip-sample-0.0.0/app.js (Application)
-> express-4.21.2/index.js (Extension)
-> express-4.21.2/lib/express.js (Extension)
-> express-4.21.2/lib/router/route.js (Extension)
-> express-4.21.2/lib/router/layer.js (Extension)
-> ❌ path-to-regexp-0.1.12/index.js (Vulnerable Component)
Vulnerability Details
Impact:
A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.
Patches:
Upgrade to path-to-regexp@0.1.13
Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.
Workarounds:
All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).
If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.
Publish Date: 2026-03-26
URL: CVE-2026-4867
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.018%
CVSS 3 Score Details (7.5)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: High
For more information on CVSS3 Scores, click here.
Suggested Fix
Type: Upgrade version
Origin: GHSA-37ch-88jc-xwx2
Release Date: 2026-03-26
Fix Resolution: path-to-regexp - 0.1.13
CVE-2026-8723
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
- express-4.21.2.tgz (Root Library)
- ❌ qs-6.13.0.tgz (Vulnerable Library)
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
opentok-sip-sample-0.0.0/app.js (Application)
-> express-4.21.2/index.js (Extension)
-> express-4.21.2/lib/express.js (Extension)
-> body-parser-1.20.3/index.js (Extension)
-> body-parser-1.20.3/lib/types/urlencoded.js (Extension)
-> qs-6.13.0/lib/index.js (Extension)
-> ❌ qs-6.13.0/lib/stringify.js (Vulnerable Component)
Vulnerability Details
Summary
"qs.stringify" throws "TypeError" when called with "arrayFormat: 'comma'" and "encodeValuesOnly: true" on an array containing "null" or "undefined". The throw is synchronous and not handled by any of qs's null-related options ("skipNulls", "strictNullHandling").
Details
In the comma + "encodeValuesOnly" branch, "lib/stringify.js:145" mapped the array through the raw encoder before joining:
obj = utils.maybeMap(obj, encoder);
"utils.encode" ("lib/utils.js:195") reads "str.length" with no null guard, so a "null" or "undefined" element throws "TypeError". "skipNulls" and "strictNullHandling" are both checked in the per-element loop below this line and never get a chance to run.
Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + "encodeValuesOnly" branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463, 2023-01-19), first released in v6.11.1.
PoC
const qs = require('qs');
qs.stringify({ a: [null, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [undefined, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [null] }, { arrayFormat: 'comma', encodeValuesOnly: true });
// TypeError: Cannot read properties of null (reading 'length')
// at encode (lib/utils.js:195:13)
// at Object.maybeMap (lib/utils.js:322:37)
// at stringify (lib/stringify.js:145:25)
Fix
"lib/stringify.js:145", applied in 21f80b3 on "main" and released as v6.15.2:
- obj = utils.maybeMap(obj, encoder);
- obj = utils.maybeMap(obj, function (v) {
-
return v == null ? v : encoder(v);
- });
"null" and "undefined" now pass through "maybeMap" unchanged and reach the "join(',')" step as-is. For "{ a: [null, 'b'] }" this produces "a=,b", matching the non-"encodeValuesOnly" comma path (which already joins before encoding and produces "a=%2Cb" for the same input). Single-element "[null]" arrays still collapse via the existing "obj.join(',') || null" and remain subject to "skipNulls" / "strictNullHandling" in the main loop.
Affected versions
">=6.11.1 <6.15.2" — fixed in v6.15.2.
The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma + "encodeValuesOnly" path differently (joining before encoding) and are not affected. Empirically verified across released versions.
Impact
Application code that calls "qs.stringify" with both "arrayFormat: 'comma'" and "encodeValuesOnly: true" (both non-default) on input that may contain a "null" or "undefined" array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The "kills the worker process" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.
The vulnerable input is a "null" or "undefined" entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal "null").
Mend Note: The description of this vulnerability differs from MITRE.
Publish Date: 2026-05-16
URL: CVE-2026-8723
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.044%
CVSS 3 Score Details (5.3)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.
Suggested Fix
Type: Upgrade version
Origin: GHSA-q8mj-m7cp-5q26
Release Date: 2026-05-16
Fix Resolution (qs): 6.15.2
Direct dependency fix Resolution (express): 4.22.2
⛑️ Automatic Remediation will be attempted for this issue.
CVE-2026-2391
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
- express-4.21.2.tgz (Root Library)
- ❌ qs-6.13.0.tgz (Vulnerable Library)
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
opentok-sip-sample-0.0.0/app.js (Application)
-> express-4.21.2/index.js (Extension)
-> express-4.21.2/lib/express.js (Extension)
-> express-4.21.2/lib/middleware/query.js (Extension)
-> qs-6.13.0/lib/index.js (Extension)
-> ❌ qs-6.13.0/lib/parse.js (Vulnerable Component)
Vulnerability Details
Summary
The "arrayLimit" option in qs does not enforce limits for comma-separated values when "comma: true" is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).
Details
When the "comma" option is set to "true" (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., "?param=a,b,c" becomes "['a', 'b', 'c']"). However, the limit check for "arrayLimit" (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in "parseArrayValue", enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.
Vulnerable code (lib/parse.js: lines ~40-50):
if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
return val.split(',');
}
if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}
return val;
The "split(',')" returns the array immediately, skipping the subsequent limit check. Downstream merging via "utils.combine" does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., "?param=,,,,,,,,..."), allocating massive arrays in memory without triggering limits. It bypasses the intent of "arrayLimit", which is enforced correctly for indexed ("a[0]=") and bracket ("a[]=") notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).
PoC
Test 1 - Basic bypass:
npm install qs
const qs = require('qs');
const payload = 'a=' + ','.repeat(25); // 26 elements after split (bypasses arrayLimit: 5)
const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };
try {
const result = qs.parse(payload, options);
console.log(result.a.length); // Outputs: 26 (bypass successful)
} catch (e) {
console.log('Limit enforced:', e.message); // Not thrown
}
Configuration:
- "comma: true"
- "arrayLimit: 5"
- "throwOnLimitExceeded: true"
Expected: Throws "Array limit exceeded" error.
Actual: Parses successfully, creating an array of length 26.
Impact
Denial of Service (DoS) via memory exhaustion.
Mend Note: The description of this vulnerability differs from MITRE.
Publish Date: 2026-02-12
URL: CVE-2026-2391
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.076%
CVSS 3 Score Details (3.7)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.
Suggested Fix
Type: Upgrade version
Origin: GHSA-w7fw-mjwx-w883
Release Date: 2026-02-12
Fix Resolution (qs): 6.14.2
Direct dependency fix Resolution (express): 4.22.0
⛑️ Automatic Remediation will be attempted for this issue.
CVE-2025-15284
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
- express-4.21.2.tgz (Root Library)
- ❌ qs-6.13.0.tgz (Vulnerable Library)
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
opentok-sip-sample-0.0.0/app.js (Application)
-> express-4.21.2/index.js (Extension)
-> express-4.21.2/lib/express.js (Extension)
-> express-4.21.2/lib/middleware/query.js (Extension)
-> qs-6.13.0/lib/index.js (Extension)
-> qs-6.13.0/lib/stringify.js (Extension)
-> ❌ qs-6.13.0/lib/utils.js (Vulnerable Component)
Vulnerability Details
Improper Input Validation vulnerability in qs (parse modules) allows HTTP DoS.This issue affects qs: < 6.14.1.
Summary
The arrayLimit option in qs did not enforce limits for bracket notation (a[]=1&a[]=2), only for indexed notation (a[0]=1). This is a consistency bug; arrayLimit should apply uniformly across all array notations.
Note: The default parameterLimit of 1000 effectively mitigates the DoS scenario originally described. With default options, bracket notation cannot produce arrays larger than parameterLimit regardless of arrayLimit, because each a[]=valueconsumes one parameter slot. The severity has been reduced accordingly.
Details
The arrayLimit option only checked limits for indexed notation (a[0]=1&a[1]=2) but did not enforce it for bracket notation (a[]=1&a[]=2).
Vulnerable code (lib/parse.js:159-162):
if (root === '[]' && options.parseArrays) {
obj = utils.combine([], leaf); // No arrayLimit check
}
Working code (lib/parse.js:175):
else if (index <= options.arrayLimit) { // Limit checked here
obj = [];
obj[index] = leaf;
}
The bracket notation handler at line 159 uses utils.combine([], leaf) without validating against options.arrayLimit, while indexed notation at line 175 checks index <= options.arrayLimit before creating arrays.
PoC
const qs = require('qs');
const result = qs.parse('a[]=1&a[]=2&a[]=3&a[]=4&a[]=5&a[]=6', { arrayLimit: 5 });
console.log(result.a.length); // Output: 6 (should be max 5)
Note on parameterLimit interaction: The original advisory's "DoS demonstration" claimed a length of 10,000, but parameterLimit (default: 1000) caps parsing to 1,000 parameters. With default options, the actual output is 1,000, not 10,000.
Impact
Consistency bug in arrayLimit enforcement. With default parameterLimit, the practical DoS risk is negligible since parameterLimit already caps the total number of parsed parameters (and thus array elements from bracket notation). The risk increases only when parameterLimit is explicitly set to a very high value.
Publish Date: 2025-12-29
URL: CVE-2025-15284
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.035%
CVSS 3 Score Details (3.7)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.
Suggested Fix
Type: Upgrade version
Origin: GHSA-6rw7-vpxm-498p
Release Date: 2025-12-29
Fix Resolution (qs): 6.14.1
Direct dependency fix Resolution (express): 4.22.0
⛑️ Automatic Remediation will be attempted for this issue.
⛑️Automatic Remediation will be attempted for this issue.
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Vulnerabilities
*For some transitive vulnerabilities, there is no version of direct dependency with a fix. Check the "Details" section below to see if there is a version of transitive dependency where vulnerability is fixed.
**In some cases, Remediation PR cannot be created automatically for a vulnerability despite the availability of remediation
Details
Vulnerable Library - path-to-regexp-0.1.12.tgz
Express style path to RegExp utility
Library home page: https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.12.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/path-to-regexp/package.json
Dependency Hierarchy:
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
Vulnerability Details
Impact:
A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in path-to-regexp@0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking.
Patches:
Upgrade to path-to-regexp@0.1.13
Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group.
Workarounds:
All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+).
If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.
Publish Date: 2026-03-26
URL: CVE-2026-4867
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.018%
CVSS 3 Score Details (7.5)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: High
For more information on CVSS3 Scores, click here.Suggested Fix
Type: Upgrade version
Origin: GHSA-37ch-88jc-xwx2
Release Date: 2026-03-26
Fix Resolution: path-to-regexp - 0.1.13
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
Vulnerability Details
Summary
"qs.stringify" throws "TypeError" when called with "arrayFormat: 'comma'" and "encodeValuesOnly: true" on an array containing "null" or "undefined". The throw is synchronous and not handled by any of qs's null-related options ("skipNulls", "strictNullHandling").
Details
In the comma + "encodeValuesOnly" branch, "lib/stringify.js:145" mapped the array through the raw encoder before joining:
obj = utils.maybeMap(obj, encoder);
"utils.encode" ("lib/utils.js:195") reads "str.length" with no null guard, so a "null" or "undefined" element throws "TypeError". "skipNulls" and "strictNullHandling" are both checked in the per-element loop below this line and never get a chance to run.
Same class of bug as the filter-array path fixed in 0c180a4. The vulnerable shape of the comma + "encodeValuesOnly" branch was introduced in 4c4b23d ("encode comma values more consistently", PR #463, 2023-01-19), first released in v6.11.1.
PoC
const qs = require('qs');
qs.stringify({ a: [null, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [undefined, 'b'] }, { arrayFormat: 'comma', encodeValuesOnly: true });
qs.stringify({ a: [null] }, { arrayFormat: 'comma', encodeValuesOnly: true });
// TypeError: Cannot read properties of null (reading 'length')
// at encode (lib/utils.js:195:13)
// at Object.maybeMap (lib/utils.js:322:37)
// at stringify (lib/stringify.js:145:25)
Fix
"lib/stringify.js:145", applied in 21f80b3 on "main" and released as v6.15.2:
"null" and "undefined" now pass through "maybeMap" unchanged and reach the "join(',')" step as-is. For "{ a: [null, 'b'] }" this produces "a=,b", matching the non-"encodeValuesOnly" comma path (which already joins before encoding and produces "a=%2Cb" for the same input). Single-element "[null]" arrays still collapse via the existing "obj.join(',') || null" and remain subject to "skipNulls" / "strictNullHandling" in the main loop.
Affected versions
">=6.11.1 <6.15.2" — fixed in v6.15.2.
The vulnerable code shape was introduced in 4c4b23d and first shipped in v6.11.1. Earlier versions — including all of 6.7.x, 6.8.x, 6.9.x, 6.10.x, and 6.11.0 — implemented the comma + "encodeValuesOnly" path differently (joining before encoding) and are not affected. Empirically verified across released versions.
Impact
Application code that calls "qs.stringify" with both "arrayFormat: 'comma'" and "encodeValuesOnly: true" (both non-default) on input that may contain a "null" or "undefined" array element will throw synchronously instead of producing a query string. In a typical Node.js HTTP framework (Express, Fastify, Koa, hapi) the sync throw is caught by the framework's error boundary and the affected request returns a 500; the worker process does not exit and subsequent requests are unaffected. The "kills the worker process" framing applies only to call sites outside a request-handler error boundary (background jobs, startup paths, stream pipelines) or to deployments with framework error handling explicitly disabled.
The vulnerable input is a "null" or "undefined" entry inside an array; this is reachable from JSON request bodies or from application code constructing arrays from user input, but not from standard HTML form submissions (which produce strings or omitted fields, not literal "null").
Mend Note: The description of this vulnerability differs from MITRE.
Publish Date: 2026-05-16
URL: CVE-2026-8723
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.044%
CVSS 3 Score Details (5.3)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.Suggested Fix
Type: Upgrade version
Origin: GHSA-q8mj-m7cp-5q26
Release Date: 2026-05-16
Fix Resolution (qs): 6.15.2
Direct dependency fix Resolution (express): 4.22.2
⛑️ Automatic Remediation will be attempted for this issue.
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
Vulnerability Details
Summary
The "arrayLimit" option in qs does not enforce limits for comma-separated values when "comma: true" is enabled, allowing attackers to cause denial-of-service via memory exhaustion. This is a bypass of the array limit enforcement, similar to the bracket notation bypass addressed in GHSA-6rw7-vpxm-498p (CVE-2025-15284).
Details
When the "comma" option is set to "true" (not the default, but configurable in applications), qs allows parsing comma-separated strings as arrays (e.g., "?param=a,b,c" becomes "['a', 'b', 'c']"). However, the limit check for "arrayLimit" (default: 20) and the optional throwOnLimitExceeded occur after the comma-handling logic in "parseArrayValue", enabling a bypass. This permits creation of arbitrarily large arrays from a single parameter, leading to excessive memory allocation.
Vulnerable code (lib/parse.js: lines ~40-50):
if (val && typeof val === 'string' && options.comma && val.indexOf(',') > -1) {
return val.split(',');
}
if (options.throwOnLimitExceeded && currentArrayLength >= options.arrayLimit) {
throw new RangeError('Array limit exceeded. Only ' + options.arrayLimit + ' element' + (options.arrayLimit === 1 ? '' : 's') + ' allowed in an array.');
}
return val;
The "split(',')" returns the array immediately, skipping the subsequent limit check. Downstream merging via "utils.combine" does not prevent allocation, even if it marks overflows for sparse arrays.This discrepancy allows attackers to send a single parameter with millions of commas (e.g., "?param=,,,,,,,,..."), allocating massive arrays in memory without triggering limits. It bypasses the intent of "arrayLimit", which is enforced correctly for indexed ("a[0]=") and bracket ("a[]=") notations (the latter fixed in v6.14.1 per GHSA-6rw7-vpxm-498p).
PoC
Test 1 - Basic bypass:
npm install qs
const qs = require('qs');
const payload = 'a=' + ','.repeat(25); // 26 elements after split (bypasses arrayLimit: 5)
const options = { comma: true, arrayLimit: 5, throwOnLimitExceeded: true };
try {
const result = qs.parse(payload, options);
console.log(result.a.length); // Outputs: 26 (bypass successful)
} catch (e) {
console.log('Limit enforced:', e.message); // Not thrown
}
Configuration:
Expected: Throws "Array limit exceeded" error.
Actual: Parses successfully, creating an array of length 26.
Impact
Denial of Service (DoS) via memory exhaustion.
Mend Note: The description of this vulnerability differs from MITRE.
Publish Date: 2026-02-12
URL: CVE-2026-2391
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.076%
CVSS 3 Score Details (3.7)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.Suggested Fix
Type: Upgrade version
Origin: GHSA-w7fw-mjwx-w883
Release Date: 2026-02-12
Fix Resolution (qs): 6.14.2
Direct dependency fix Resolution (express): 4.22.0
⛑️ Automatic Remediation will be attempted for this issue.
Vulnerable Library - qs-6.13.0.tgz
Library home page: https://registry.npmjs.org/qs/-/qs-6.13.0.tgz
Path to dependency file: /sample/SipInterconnect/package.json
Path to vulnerable library: /sample/SipInterconnect/node_modules/express/node_modules/qs/package.json
Dependency Hierarchy:
Found in base branch: main
Reachability Analysis
This vulnerability is potentially reachable
Vulnerability Details
Improper Input Validation vulnerability in qs (parse modules) allows HTTP DoS.This issue affects qs: < 6.14.1.
Summary
The arrayLimit option in qs did not enforce limits for bracket notation (a[]=1&a[]=2), only for indexed notation (a[0]=1). This is a consistency bug; arrayLimit should apply uniformly across all array notations.
Note: The default parameterLimit of 1000 effectively mitigates the DoS scenario originally described. With default options, bracket notation cannot produce arrays larger than parameterLimit regardless of arrayLimit, because each a[]=valueconsumes one parameter slot. The severity has been reduced accordingly.
Details
The arrayLimit option only checked limits for indexed notation (a[0]=1&a[1]=2) but did not enforce it for bracket notation (a[]=1&a[]=2).
Vulnerable code (lib/parse.js:159-162):
if (root === '[]' && options.parseArrays) {
obj = utils.combine([], leaf); // No arrayLimit check
}
Working code (lib/parse.js:175):
else if (index <= options.arrayLimit) { // Limit checked here
obj = [];
obj[index] = leaf;
}
The bracket notation handler at line 159 uses utils.combine([], leaf) without validating against options.arrayLimit, while indexed notation at line 175 checks index <= options.arrayLimit before creating arrays.
PoC
const qs = require('qs');
const result = qs.parse('a[]=1&a[]=2&a[]=3&a[]=4&a[]=5&a[]=6', { arrayLimit: 5 });
console.log(result.a.length); // Output: 6 (should be max 5)
Note on parameterLimit interaction: The original advisory's "DoS demonstration" claimed a length of 10,000, but parameterLimit (default: 1000) caps parsing to 1,000 parameters. With default options, the actual output is 1,000, not 10,000.
Impact
Consistency bug in arrayLimit enforcement. With default parameterLimit, the practical DoS risk is negligible since parameterLimit already caps the total number of parsed parameters (and thus array elements from bracket notation). The risk increases only when parameterLimit is explicitly set to a very high value.
Publish Date: 2025-12-29
URL: CVE-2025-15284
Threat Assessment
Exploit Maturity: Not Defined
EPSS: 0.035%
CVSS 3 Score Details (3.7)
Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: High
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: Low
For more information on CVSS3 Scores, click here.Suggested Fix
Type: Upgrade version
Origin: GHSA-6rw7-vpxm-498p
Release Date: 2025-12-29
Fix Resolution (qs): 6.14.1
Direct dependency fix Resolution (express): 4.22.0
⛑️ Automatic Remediation will be attempted for this issue.
⛑️Automatic Remediation will be attempted for this issue.