Open WebUI server hang vulnerability via cyclic chat message deletion

# Open WebUI server hang vulnerability via cyclic chat message deletion

https://gcdradar.vercel.app/incidents/open-webui-server-hang-vulnerability-via-cyclic-chat-message · AIR-2026-0905 · closed 2026-09-09

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-09-09
- AI role: Attack on AI
- Products: Open WebUI
- CVE ids: CVE-2026-88000
- CVSS: 6.5

## Summary

An unvalidated JSON structure in chat histories allowed authenticated users to trigger an infinite loop by deleting messages in a cyclic chat tree. This infinite loop blocks server requests until the process is restarted.

## What to do

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

## Latest updates

- 2026-09-09: CVE-2026-88000: Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. (https://nvd.nist.gov/vuln/detail/CVE-2026-88000)
- 2026-09-09: CVE-2026-88000: Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree (https://github.com/advisories/GHSA-3cgp-3cqx-j8w2)

## Sources

- 2026-09-09 GitHub Advisory Database: CVE-2026-88000: Open WebUI: Any authenticated user can hang the server via message deletion in a cyclic chat tree https://github.com/advisories/GHSA-3cgp-3cqx-j8w2
- 2026-09-09 NVD: CVE-2026-88000: Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. https://nvd.nist.gov/vuln/detail/CVE-2026-88000

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