CVE-2026-35339 is a medium-severity (CVSS 5.5) CWE-253 vulnerability in uu_chmod. A fix is available for uu_chmod — see the affected versions and patch details below.
uutils coreutils chmod False Success Exit Code in Recursive Mode
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-35339.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
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
In Chmoder::chmod() the recursive branch overwrites the running result instead of accumulating it, so the exit code reflects only the last file processed:
if self.recursive {
r = self.walk_dir_with_context(file, true); // overwrites r
} else {
r = self.chmod_file(file).and(r);
}
PoC: GNU returns 1 when a file fails; uutils returns 0 if the last entry succeeds:
$ chmod -R 0755 chmod-bug/root chmod-bug/user # GNU -> ret=1
$ uutils chmod -R 0755 chmod-bug/root chmod-bug/user # -> ret=0
Impact: scripts relying on the exit code get a false success signal while some files retained restrictive/unexpected permissions, leading to access-control misconfigurations. Recommendation: accumulate errors during traversal.
Remediation: Acknowledged by Canonical; fixed in commit abd581f6.
Reported by Zellic in the uutils coreutils Program Security Assessment (prepared for Canonical, Jan 20 2026), audited commit 3a07ffc5a9bd4c283e75afa548ba1f1957bad242. Finding 3.2. Credit: Zellic.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | uu_chmod | all versions | 0.6.0cargo update -p uu_chmod --precise 0.6.0 |
Affected Products
coreutilsuutilsDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for uu_chmod, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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.
Frequently Asked Questions
Is CVE-2026-35339 in your dependencies?
Find it across crates.io, including transitive dependencies.