CVE-2026-35592: pyLoad has an Incomplete Tar Path Traversal Fix in UnTar._safe_extractall via os.path.commonprefix Bypass

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-07 · updated 2026-06-17
Weakness: CWE-22

Description

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev97, the _safe_extractall() 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 CVE-2026-32808 fix (commit 5f4f0fa) but was never applied to _safe_extractall(), making this an incomplete fix. This vulnerability is fixed in 0.5.0b3.dev97.

Affected products

pyload: through 0.5.0b3.dev96

References

https://github.com/pyload/pyload/security/advisories/GHSA-mvwx-582f-56r7

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