🛡️ Sentinel: [HIGH] Fix CSV formula injection bypass with NUL byte

[seonghobae]

🛡️ Sentinel: [HIGH] Fix CSV formula injection bypass with NUL byte

* 🚨 Severity: HIGH
* 💡 Vulnerability: CSV formula injection mitigation in the export module missed checking for the NUL byte (`\x00`).
* 🎯 Impact: An attacker could prepend a NUL byte which bypasses the check but is still evaluated by applications like Excel.
* 🔧 Fix: Include the NUL byte `\x00` in the regex character class checking for problematic leading characters. Added the appropriate eslint ignore comment.
* ✅ Verification: Tests added and run successfully. Monorepo quickcheck passed.

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PR created automatically by Jules for task 18406434902956248137 started by @seonghobae

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📥 Commits

Reviewing files that changed from the base of the PR and between 749511c and 29a51db.

📒 Files selected for processing (3)

• .jules/sentinel.md
• apps/desktop/src/lib/export.test.ts
• apps/desktop/src/lib/export.ts

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[seonghobae]

Superseded by canonical CSV export security owner #1103 after exact semantic comparison on the current heads.

Source examined: #1155 29a51dbece4a21d9312ff77046a7fcdf46a041ec against protected develop@749511c3ad4000090048718f685c6bee6b3d2c25.
Successor examined: #1103 910636e2d1f6d4b9acf4345829247c8af20987b1 against the same protected base.

The #1155 diff is exactly the same three-file desktop CSV boundary (apps/desktop/src/lib/export.ts, apps/desktop/src/lib/export.test.ts, .jules/sentinel.md). Its production delta adds NUL to the dangerous-leading-token regex. #1103 already contains that NUL guard and a strictly broader full-width operator guard. Its executable regressions include the exact \x00=1+2 case, whitespace-before-NUL, repeated-NUL, whitespace+repeated-NUL, and NUL-only cells. The #1155 \x00cmd assertion is not a distinct behavior/contract: #1103 explicitly treats NUL itself as the dangerous first token, demonstrated by the stronger NUL-only regression, so suffix content cannot bypass the same branch. #1155's one-space-before-NUL case is the same *-quantified prefix class already exercised by #1103's whitespace-before-NUL cases. The sentinel note is also subsumed by #1103's stronger repeated-NUL/NUL-only trust-boundary lesson.

No unique production behavior, test requirement, fixture, contract, or evidence remains in #1155 after this comparison. No check, review, approval, or workflow result transfers to #1103; #1103 must satisfy all current exact-head gates independently. Closing #1155 unmerged removes a competing writer without discarding a valid delta.

[google-labs-jules]

Superseded by canonical CSV export security owner #1103 after exact semantic comparison on the current heads.

Source examined: #1155 29a51dbece4a21d9312ff77046a7fcdf46a041ec against protected develop@749511c3ad4000090048718f685c6bee6b3d2c25.
Successor examined: #1103 910636e2d1f6d4b9acf4345829247c8af20987b1 against the same protected base.

The #1155 diff is exactly the same three-file desktop CSV boundary (apps/desktop/src/lib/export.ts, apps/desktop/src/lib/export.test.ts, .jules/sentinel.md). Its production delta adds NUL to the dangerous-leading-token regex. #1103 already contains that NUL guard and a strictly broader full-width operator guard. Its executable regressions include the exact \x00=1+2 case, whitespace-before-NUL, repeated-NUL, whitespace+repeated-NUL, and NUL-only cells. The #1155 \x00cmd assertion is not a distinct behavior/contract: #1103 explicitly treats NUL itself as the dangerous first token, demonstrated by the stronger NUL-only regression, so suffix content cannot bypass the same branch. #1155's one-space-before-NUL case is the same *-quantified prefix class already exercised by #1103's whitespace-before-NUL cases. The sentinel note is also subsumed by #1103's stronger repeated-NUL/NUL-only trust-boundary lesson.

No unique production behavior, test requirement, fixture, contract, or evidence remains in #1155 after this comparison. No check, review, approval, or workflow result transfers to #1103; #1103 must satisfy all current exact-head gates independently. Closing #1155 unmerged removes a competing writer without discarding a valid delta.

Understood. Acknowledging that this work is now obsolete (superseded by #1103) and stopping work on this task.