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Vulnerability · Published Aug 4, 2026 · Assigned by GitHub_M

CVE-2026-70493Open WebUI: Any authenticated user can stall a worker via a knowledge-search pattern that backtracks catastrophically

Medium 6.5

In plain English

A medium-severity regular-expression denial of service in open-webui from open-webui. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.6%top 51.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
PyPIopen-webui0.11.0GHSA-2f54-p244-32q6
PyPIopen-webui0.11.0PYSEC-2026-3637

Affected products (as reported)

VendorProductVersions
open-webui open-webui >= 0.9.6, < 0.11.0

Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References