CVE-2026-109295 open-webui CVE debrief

Who should care

Defenders responsible for Open WebUI deployments should assess exposure and prioritize verification and remediation efforts. This includes operators, platform administrators, vulnerability management teams, and security teams who need to verify Open WebUI version and monitor for suspicious activity.

Why it matters

CVE-2026-109295 is a regular expression denial of service vulnerability in Open WebUI versions 0.11.0 before 0.11.4. Authenticated users can cause denial of service by providing specially crafted file search patterns. Defenders should prioritize verifying and updating Open WebUI and monitoring for suspicious activity.

• Denial of service via blocking server workers
• Potential for prolonged service disruption with repeated exploitation
• Need for verification of Open WebUI version and monitoring for suspicious activity

Technical summary

The Open WebUI application versions 0.11.0 before 0.11.4 are vulnerable to a regular expression denial of service (ReDoS) attack. An authenticated user can provide a specially crafted file search pattern that triggers catastrophic backtracking in the regex, causing the server worker to block for two seconds per repeated call. This vulnerability affects Open WebUI deployments, and defenders should prioritize verifying and updating Open WebUI to version 0.11.4 or later, and monitoring for suspicious file search patterns.

Defensive priority

Defenders should prioritize verifying and updating Open WebUI to version 0.11.4 or later, and monitoring for suspicious file search patterns.

Recommended defensive actions

• Verify Open WebUI version and update to 0.11.4 or later if necessary
• Monitor for suspicious file search patterns
• Implement additional security measures to prevent authenticated users from causing denial of service
• 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 CVE record and source item provide details on the vulnerability, but do not offer specific information on exploitation or victim impact. The Open WebUI application is vulnerable to a regular expression denial of service (ReDoS) attack, which can be triggered by authenticated users providing specially crafted file search patterns. There is no information on known or unknown affected scope, but defenders should verify Open WebUI version and monitor for suspicious activity.

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.