CVE-2026-70493 open-webui CVE debrief

Who should care

Users of Open WebUI versions between 0.9.6 and 0.11.0 should be aware of this vulnerability and take necessary actions to mitigate the risk. This includes updating to version 0.11.0 or later, restricting access to the affected components, and monitoring for suspicious patterns in knowledge search queries.

Technical summary

The CVE-2026-70493 vulnerability exists in Open WebUI versions from 0.9.6 until 0.11.0. It allows a chat participant to choose a pattern used to grep knowledge files, potentially causing a denial of service via crafted regex patterns. The vulnerability is caused by the compilation of patterns containing regex metacharacters with Python's backtracking re engine, which can run against every line of every reachable file with no time limit. A crafted pattern can pin one CPU core and block the event loop, impacting availability for other users of the affected worker.

Defensive priority

Medium-severity vulnerability in Open WebUI, allowing for denial of service via crafted regex patterns.

Recommended defensive actions

• Review and update Open WebUI to version 0.11.0 or later
• Restrict access to the affected components
• Monitor for suspicious patterns in knowledge search queries
• Implement additional logging and monitoring for the Open WebUI platform
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The CVE-2026-70493 issue allows a chat participant to choose a pattern used to grep knowledge files, potentially causing a denial of service via crafted regex patterns. The vulnerability exists in Open WebUI versions from 0.9.6 until 0.11.0, specifically in the files backend/open_webui/tools/knowledge_fs.py and backend/open_webui/tools/builtin.py. A crafted pattern can pin one CPU core and block the event loop, impacting availability for other users of the affected worker.

Official resources