pyload-ng: Incomplete Tar Path Traversal Fix in UnTar._safe_extractall via os.path.commonprefix Bypass

Exploitation

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

CVSS

5.3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-35592: 0.26% estimated exploitation activity in the next 30 days; percentile 17.19 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The safeextractall() function in src/pyload/plugins/extractors/UnTar.py uses os.path.commonprefix() for its path traversal check, which performs character-level string comparison rather than path-level comparison. This allows a specially crafted tar archive to write files outside the intended extraction directory. The correct function os.path.commonpath() was added to the codebase in the GHSA-7g4m-8hx2-4qh3 fix (commit 5f4f0fa) but was never applied to safeextractall(), making this an incomplete fix. Details The GHSA-7g4m-8hx2-4qh3 fix (commit 5f4f0fa) added a correct iswithindirectory() function to src/pyload/core/utils/fs.py:384-391 using os.path.commonpath(): However, the safeextractall() function in UnTar.py:10-22 was left unchanged with the broken os.path.commonprefix(): os.path.commonprefix() is a string operation, not a path operation. For extraction destination /downloads/pkg and a malicious member ../pkgevil/payload (resolving to /downloads/pkgevil/payload): -…

Published by the source

8 Apr 2026, 00:04 UTC

Last modified by the source

8 Jun 2026, 20:00 UTC

Source last checked

26 Oct 2026, 13:44 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mvwx-582f-56r7

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mvwx-582f-56r7

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# Patch Next advisory brief: CVE-2026-35592

Advisory: pyload-ng: Incomplete Tar Path Traversal Fix in UnTar._safe_extractall via os.path.commonprefix Bypass
IDs: CVE-2026-35592, GHSA-mvwx-582f-56r7
Record: https://patchnext.com/advisories/cve-2026-35592 (revision 2, source checked 26 Oct 2026, 13:44 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pyload-ng 0.5.0b3.dev97. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pyload-ng: affected < 0.5.0b3.dev97; fixed in 0.5.0b3.dev97

## Suggested inspection (read-only)
- `python -m pip show pyload-ng`: 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 pyload-ng.
- 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-mvwx-582f-56r7 (OSV record GHSA-mvwx-582f-56r7 lists affected ranges: PyPI pyload-ng >=0 <0.5.0b3.dev97 (fixed))
- Verified: https://github.com/advisories/GHSA-mvwx-582f-56r7 (GitHub-reviewed advisory GHSA-mvwx-582f-56r7 lists affected ranges: PyPI pyload-ng >=0 <0.5.0b3.dev97)

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