CVE-2026-87015 open-webui CVE debrief

Who should care

Defenders and administrators of Open WebUI installations should assess exposure and prioritize upgrading to version 0.11.1. They should verify their Open WebUI version and review configurations for tool servers. Security teams should monitor for suspicious activity and review compensating controls for exposed systems.

Why it matters

Defenders should care about CVE-2026-87015 as it could allow unauthorized account takeover in Open WebUI installations. Administrators should verify their version and upgrade to 0.11.1 if necessary.

• Potential unauthorized account takeover
• Session cookie sharing across tool servers
• Need for version verification and upgrade

Technical summary

The Open WebUI platform had a vulnerability where session cookies could be shared across tool servers, potentially allowing unauthorized account takeover. This issue was fixed in version 0.11.1. The vulnerability was caused by the improper binding of session cookies to each external tool callable. Defenders should prioritize verifying their Open WebUI version and upgrading to 0.11.1 if necessary. The issue allowed an attacker to reuse session cookies across different tool servers configured for bearer authentication.

Defensive priority

Defenders should prioritize verifying their Open WebUI version and upgrading to 0.11.1 if necessary.

Recommended defensive actions

• Verify Open WebUI version and upgrade to 0.11.1 if necessary
• Review and update configurations for tool servers
• Monitor for suspicious activity
• 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 was reported in Open WebUI versions 0.6.27 to 0.11.1. Session cookies could be shared across tool servers, potentially allowing account takeover. The issue was fixed in version 0.11.1. Defenders should verify their Open WebUI version and upgrade if necessary. The vulnerability was caused by the capturing of a cookie jar from the enclosing connection loop instead of binding it to each external tool callable.

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.