GHSA-pqhf-p39g-3x64
uv allows ZIP payload obfuscation through parsing differentials
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
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Description
Impact
In versions 0.9.5 and earlier of uv, ZIP archives were handled in a manner that enabled two parsing differentials against other components of the Python packaging ecosystem:
- Central directory entries in a ZIP archive can contain comment fields. However, uv would assume that these fields were not present, since they aren't widely used. Consequently, a ZIP archive could be constructed where uv would interpret the contents of a central directory comment field as ZIP control structures (such as a new central directory entry), rather than skipping over them.
- Both local file entries and central directory entries contain filename fields, which are used to place archive members on disk. These fields are arbitrary sequences of bytes, and may therefore be invalid or ambiguous. For example, they may contain ASCII null bytes, in which case different ZIP extractors behave differently: Python's
zipfilemodule truncates the filename at the first null, while uv would skip (not extract) any archive members whose filenames contained nulls. Because of this difference, a ZIP archive could be constructed that would extract differently across different Python package installers.
In both cases, the outcome is that an attacker may be able to produce a ZIP with a consistent digest that expands differently with different Python package installers.
Like with GHSA-8qf3-x8v5-2pj8, the impact of these differentials is limited by a number of factors:
- To be compromised via this vulnerability, user interaction of some sort is required. In particular, the user must run
uv pip install $packageor similar with an attacker-controlled $package. When using wheel distributions, installation of the malicious package is not sufficient for execution of malicious code, the vicim would need to perform a separate invocation, e.g.,python -c "import $package". - If a ZIP-based source distribution (which are less common than tarball source distributions), is encountered, malicious code can be executed during package resolution or installation. uv may invoke the malicious code when building the source distribution into a wheel.
Patches
Versions 0.9.6 and newer of uv address both of the parser differentials above, by properly handling comments in central directory entries and by refusing to process ZIPs that contain filename fields that are unlikely to be interpreted consistently across other ZIP parser implementations.
Workarounds
Users are advised to upgrade to 0.9.6 or newer to address this advisory.
Most users should experience no breaking changes as a result of the patch above. However, users who do experience breakage should carefully review their distributions for signs of malicious intent. Users may choose to set UV_INSECURE_NO_ZIP_VALIDATION=1 to revert to the previous behavior.
Attribution
This vulnerability was disclosed by Caleb Brown (Google).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | uv | all versions | 0.9.6 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for uv. 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 uv to 0.9.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pqhf-p39g-3x64 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 GHSA-pqhf-p39g-3x64 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 GHSA-pqhf-p39g-3x64. 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-pqhf-p39g-3x64 in your dependencies?
O3 detects GHSA-pqhf-p39g-3x64 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.