CVE-2026-40256 Weblate: Prefix-Based Repository Boundary Check Bypass via Symlink/Junction Path Prefix Collision
Attackers can bypass repository boundary checks via symlink or junction path prefix collisions to access or modify files outside the intended repository.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40256?
CVE-2026-40256 is a medium-severity path traversal vulnerability in WeblateOrg weblate, published on 15 Apr 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Weblate is a web based localization tool. In versions prior to 5.17, 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). This issue has been fixed in version 5.17.
Weakness: CWE-22
Which versions are affected by CVE-2026-40256?
3 open source packages ship an affected version, including weblate. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
weblate PyPI | All versions | 5.17 |
weblate PyPI | All versions | 5.17 |
weblate PyPI | All versions | 5.17 |
Products include Weblate Weblate.
How do I fix CVE-2026-40256?
Upgrade weblate to 5.17 or later.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-40256 being exploited?
There is no known exploitation of CVE-2026-40256 in the wild and no public exploit code.
Other vulnerabilities in WeblateOrg weblate
- CVE-2025-68398 Weblate has git config file overwrite vulnerability that leads to remote code execution
- CVE-2026-34393 Weblate: Privilege escalation in the user API endpoint
- CVE-2026-33435 Weblate: Remote code execution during backup restoration
- CVE-2026-34242 Weblate: Arbitrary File Read via Symlink
- CVE-2025-68279 Weblate has an arbitrary file read via symbolic links
Sources
Also known as GHSA-ffgh-3jrf-8wvh, PYSEC-2026-2315.