CVE-2026-82720 (Medium) detected in src4.0.4, src4.0.4 #536

Vulnerable Libraries - src4.0.4, src4.0.4

src4.0.4

MidnightBSD OS source code

Library home page: https://github.com/MidnightBSD/src.git

Vulnerable Source Files (1)

/contrib/unbound/util/netevent.c

src4.0.4

MidnightBSD OS source code

Library home page: https://github.com/MidnightBSD/src.git

Vulnerable Source Files (1)

/contrib/unbound/util/netevent.c

Found in base branches: stable/4.0, master

Vulnerability Details

NLnet Labs Unbound 1.12.0 up to and including 1.26.0 has a use-after-free vulnerability when compiled for DNS-over-HTTPs support with '--with-libnghttp2'. During failure code paths (i.e., RPZ drop query, jostle due to heavy traffic), a dropped DoH stream brings down the whole DoH session and does not account properly for other DoH streams in the same session. This leads to use-after-free in those code paths. If the prerequisites are satisfied (possible RPZ drop or heavy client traffic), a malicious actor can trigger the vulnerability with a single DoH connection and the appropriate traffic. Impact is limited as the reads are not user controlled and the use-after-free leads to early returns. However, a hardened allocator can catch the use-after-free and controllably terminate the process resulting to denial of service.

Publish Date: 2026-09-16

URL: CVE-2026-82720

CVSS 3 Score Details (5.9)

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: High