CVE-2026-87015: Open WebUI Session Cookie Leak to Tool Servers

# CVE-2026-87015: Open WebUI Session Cookie Leak to Tool Servers

https://gcdradar.vercel.app/incidents/cve-2026-87015-open-webui-session-cookie-leak-to-tool-server · AIR-2026-0909 · closed 2026-09-09

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-09-09 (happened 2026-09-10)
- AI role: Attack on AI
- Products: Open WebUI
- CVE ids: CVE-2026-87015
- CVSS: 6.8

## Summary

Open WebUI improperly handles session cookies when multiple external tool servers are called in a single request, leaking authentication cookies to unintended endpoints. The issue arises from late cookie jar evaluation across connections.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-09-10: CVE-2026-87015: Open WebUI: A user's session cookies are sent to tool servers configured for bearer authentication (https://github.com/advisories/GHSA-p78m-89r6-pgf7)
- 2026-09-09: CVE-2026-87015: Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. (https://nvd.nist.gov/vuln/detail/CVE-2026-87015)

## Sources

- 2026-09-09 NVD: CVE-2026-87015: Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. https://nvd.nist.gov/vuln/detail/CVE-2026-87015
- 2026-09-10 GitHub Advisory Database: CVE-2026-87015: Open WebUI: A user's session cookies are sent to tool servers configured for bearer authentication https://github.com/advisories/GHSA-p78m-89r6-pgf7

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.