CVE-2026-70493 open-webui CVE debrief

Who should care

Defenders of Open WebUI instances, especially those with untrusted user access, should assess exposure and prioritize patching to prevent potential DoS attacks. The vulnerability allows a crafted regex pattern to cause a DoS attack, impacting availability for other users of the affected worker. Security teams and platform operators should review the patching status of Open WebUI instances and monitor for suspicious activity. 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Why it matters

Defenders should prioritize patching Open WebUI to prevent potential DoS attacks, especially in environments with untrusted user access. The vulnerability allows a crafted regex pattern to cause a DoS attack, impacting availability for other users of the affected worker. The attack requires a valid chat participant to submit a crafted pattern.

• Denial of service (DoS) attacks against the affected worker
• Potential impact on availability for other users of the affected worker

Technical summary

The built-in knowledge search path in Open WebUI allows a chat participant to choose a pattern used to grep knowledge files. Patterns containing regex metacharacters are compiled with Python's backtracking re engine and run against every line of every reachable file with no time limit. This can lead to a denial-of-service (DoS) attack, impacting availability for other users of the affected worker. The attack requires a valid chat participant to submit a crafted 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Defensive priority

Defenders should prioritize patching to prevent potential DoS attacks, especially in environments with untrusted user access.

Recommended defensive actions

• Patch Open WebUI to version 0.11.0 or later
• Restrict access to the affected worker
• Monitor for suspicious regex patterns
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by the use of Python's backtracking re engine to compile and run regex patterns against every line of every reachable file with no time limit. This allows a crafted pattern, such as (x|x)*y, to pin one CPU core and block the event loop, leading to a denial-of-service (DoS) attack. The attack requires a valid chat participant to submit a crafted pattern. There is no evidence of in-the-wild exploitation, but defenders should verify the patching status of Open WebUI instances and monitor for suspicious regex 0

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.