GHSA-w476-p2h3-79g9 — uv
Fix: astral-sh/uv#16387GHSA-w476-p2h3-79g9 is a remote code execution vulnerability in uv. A fix is available for uv — see the affected versions and patch details below.
uv has differential in tar extraction with PAX headers
Real-World Exposure
uvReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
In versions 0.9.4 and earlier of uv, tar archives containing PAX headers with file size overrides were not handled properly. As a result, an attacker could contrive a source distribution (as a tar archive) that would extract differently when installed via uv versus other Python package installers.
The underlying parsing differential here originates with astral-tokio-tar, which disclosed this vulnerability as CVE-2025-62518.
In practice, the impact of this vulnerability is low: only source distributions can be formatted as tar archives, and source distributions execute arbitrary code at build/installation time by definition. Consequently, a parser differential in tar extraction is strictly less powerful than the capabilities already exposed to an attacker who has the ability to control source distributions.
However, this particular source of malleability in source distributions is unintentional and not operating by design, and therefore we consider it a vulnerability despite its overlap in capabilities with intended behavior.
Patches
Versions 0.9.5 and newer of uv address the vulnerability above. Users should upgrade to 0.9.5 or newer.
Workarounds
Users are advised to upgrade to version 0.9.5 or newer to address this advisory.
Users should experience no breaking changes as a result of the patch above.
References
- See CVE-2025-62518 for the corresponding advisory against astral-tokio-tar
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | uv | all versions | 0.9.5pip install --upgrade 'uv==0.9.5' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for uv, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update uv to 0.9.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-w476-p2h3-79g9 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-w476-p2h3-79g9 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-w476-p2h3-79g9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-w476-p2h3-79g9 in your dependencies?
O3 Security finds GHSA-w476-p2h3-79g9 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.