CVE-2026-21866

Dify - Stored XSS in chat

CVSS 5.1 MEDIUMEPSS 0.2%CWE-79

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 5.1EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

03 Mar 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Affected products

langgenius · dify

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References

https://github.com/langgenius/dify/commit/ae17537470bba417a8971fff705dd82ecb043564 https://github.com/langgenius/dify/pull/29811 https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4