Description
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.6 until 0.11.0, the built-in knowledge search path in backend/open_webui/tools/knowledge_fs.py and backend/open_webui/tools/builtin.py let a chat participant choose a pattern used to grep knowledge files. Patterns containing regex metacharacters were compiled with Python's backtracking re engine and run against every line of every reachable file with no time limit, so a crafted pattern such as (x|x)*y and one matching uploaded file line can pin one CPU core and block the event loop. This causes availability impact for every other user of the affected worker. This issue is fixed in 0.11.0.
Affected products
openwebui: open webui
References5
- github.com/open-webui/open-webui/pull/27471 PatchVendor Advisory
- github.com/open-webui/open-webui/security/advisories/GHSA-2f54-… ExploitPatchVendor Advisory
- github.com/open-webui/open-webui/security/advisories/GHSA-2f54-… ExploitPatchVendor Advisory
- github.com/open-webui/open-webui/commit/3ab2026262ef6f09810e4d2… Patch
- github.com/open-webui/open-webui/releases/tag/v0.11.0 Release Notes
Metrics
- CVSS 3.1
-
6.5
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 49 · as of 13 November 2026
- CWE
- CWE-1333
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.