CVE-2026-35339 is a medium-severity (CVSS 5.5) CWE-253 vulnerability in uu_chmod. O3 Security confirms whether CVE-2026-35339 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
uutils coreutils chmod False Success Exit Code in Recursive Mode
Real-World Exposure
uu_chmodReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
The recursive mode (-R) of the chmod utility in uutils coreutils incorrectly handles exit codes when processing multiple files. The final return value is determined solely by the success or failure of the last file processed. This allows the command to return an exit code of 0 (success) even if errors were encountered on previous files, such as 'Operation not permitted'. Scripts relying on these exit codes may proceed under a false sense of success while sensitive files remain with restrictive or incorrect permissions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | uu_chmod | all versions | 0.6.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for uu_chmod. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update uu_chmod to 0.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35339 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-35339 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-35339. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-35339 in your dependencies?
O3 detects CVE-2026-35339 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.