CVE-2026-87994 open-webui CVE debrief

Who should care

Defenders responsible for Open WebUI deployments, especially those using versions between 0.9.5 and 0.11.1, should assess exposure and verify conversation records for potential tampering.

Why it matters

Defenders should care about CVE-2026-87994 because it allows a channel member to alter conversation records in Open WebUI without gaining broader access, potentially impacting data integrity and requiring verification of user authentication for message authorship.

• Conversation record tampering without access gain
• Potential data integrity issues in conversation history
• Verification of user authentication for message authorship required
• Remediation priority for Open WebUI versions 0.9.5 to 0.11.0

Technical summary

The channel branch of chat_completion in backend/open_webui/main.py did not verify that the calling user authored the targeted message, allowing a channel member to replace another member's message while preserving the victim as the stored author. This issue, fixed in version 0.11.1, affects Open WebUI versions between 0.9.5 and 0.11.1. The vulnerability enables conversation record tampering without access gain, potentially impacting data integrity and requiring verification of user authentication for message authorship.

Defensive priority

Defenders should prioritize verifying exposure and assessing the impact of this vulnerability on their systems, especially those using Open WebUI versions between 0.9.5 and 0.11.1.

Recommended defensive actions

• Verify Open WebUI version and assess exposure
• Review conversation records for potential tampering
• Update to version 0.11.1 or later if vulnerable
• 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
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the corpus does not establish versions, exploitation, impact, or remediation beyond vendor-provided information.

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.