uv has differential in tar extraction with PAX headers

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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…

Published by the source

21 Oct 2025, 18:53 UTC

Last modified by the source

4 Feb 2026, 02:52 UTC

Source last checked

26 Oct 2026, 13:35 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-w476-p2h3-79g9

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-w476-p2h3-79g9

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# Patch Next advisory brief: GHSA-w476-p2h3-79g9

Advisory: uv has differential in tar extraction with PAX headers
IDs: GHSA-w476-p2h3-79g9
Record: https://patchnext.com/advisories/ghsa-w476-p2h3-79g9 (revision 2, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: uv 0.9.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI uv: affected <= 0.9.4; fixed in 0.9.5

## Suggested inspection (read-only)
- `python -m pip show uv`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on uv.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-w476-p2h3-79g9 (OSV record GHSA-w476-p2h3-79g9 lists affected ranges: PyPI uv >=0 <0.9.5 (fixed))
- Verified: https://github.com/advisories/GHSA-w476-p2h3-79g9 (GitHub-reviewed advisory GHSA-w476-p2h3-79g9 lists affected ranges: PyPI uv >=0 <=0.9.4)

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