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MEDIUM severity

Weblate: Prefix-Based Repository Boundary Check Bypass via Symlink/Junction Path Prefix CollisionGHSA-ffgh-3jrf-8wvh

MEDIUMFix: WeblateOrg/weblate#18847

GHSA-ffgh-3jrf-8wvh is a medium-severity (CVSS 5) Path Traversal vulnerability in weblate. A fix is available for weblate — see the affected versions and patch details below.

Also known asCVE-2026-40256PYSEC-2026-2315
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-ffgh-3jrf-8wvh.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs26th percentile — riskier than 26% of all scored CVEsHighest risk
0.00%0.29%0.58%0.87%0.0%0.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍weblate

Real-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

Weblate repository-boundary validation relies on string prefix checks on resolved absolute paths. In multiple code paths, the check uses startswith against the repository root path. This is not path-segment aware and can be bypassed when the external path shares the same string prefix as the repository path (for example, repo and repo_outside).

Patches

References

Thanks to m9nx4u for reporting this issue via HackerOne.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIweblateall versions5.17pip install --upgrade 'weblate==5.17'

Affected Products

1 product · 1 configurations
Application
weblateweblate
< 5.17
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for weblate, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update weblate to 5.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ffgh-3jrf-8wvh is resolved across your whole dependency graph.

  3. Workarounds

    Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Frequently Asked Questions

### Impact Weblate repository-boundary validation relies on string prefix checks on resolved absolute paths. In multiple code paths, the check uses startswith against the repository root path. This is not path-segment aware and can be bypassed when the external path shares the same string prefix as the repository path (for example, repo and repo_outside). ### Patches * https://github.com/WeblateOrg/weblate/pull/18847 ### References Thanks to [m9nx4u](https://hackerone.com/m9nx4u) for reporting this issue via HackerOne.
O3 Security · Impact-Aware SCA

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Weblate: Prefix-Based Repository Boundary Check…