Vulnerability Description
Dify is an open-source LLM app development platform. Prior to 1.11.2, Dify is vulnerable to a stored XSS issue when rendering Mermaid diagrams within chats. This occurs because Dify’s default Mermaid configuration uses securityLevel: loose, which allows potentially unsafe content to execute. This vulnerability is fixed in 1.11.2.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Dify | Dify | < 1.11.2 |
Related Weaknesses (CWE)
References
- https://github.com/langgenius/dify/commit/ae17537470bba417a8971fff705dd82ecb0435Patch
- https://github.com/langgenius/dify/pull/29811Issue TrackingPatch
- https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4ExploitVendor Advisory
FAQ
What is CVE-2026-21866?
CVE-2026-21866 is a vulnerability with a CVSS score of 5.4 (MEDIUM). Dify is an open-source LLM app development platform. Prior to 1.11.2, Dify is vulnerable to a stored XSS issue when rendering Mermaid diagrams within chats. This occurs because Dify’s default Mermaid ...
How severe is CVE-2026-21866?
CVE-2026-21866 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-21866?
Check the references section above for vendor advisories and patch information. Affected products include: Dify Dify.