CVE-2026-21866
Dify - Stored XSS in chat
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.
INFO
Published Date :
March 3, 2026, 10:16 p.m.
Last Modified :
March 5, 2026, 9:24 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Dify to version 1.11.2.
- Review Mermaid diagram rendering security settings.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-21866.
| URL | Resource |
|---|---|
| https://github.com/langgenius/dify/commit/ae17537470bba417a8971fff705dd82ecb043564 | Patch |
| https://github.com/langgenius/dify/pull/29811 | Issue Tracking Patch |
| https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-21866 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-21866
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-21866 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-21866 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Mar. 05, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:dify:dify:*:*:*:*:*:*:*:* versions up to (excluding) 1.11.2 Added Reference Type GitHub, Inc.: https://github.com/langgenius/dify/commit/ae17537470bba417a8971fff705dd82ecb043564 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/langgenius/dify/pull/29811 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4 Types: Exploit, Vendor Advisory -
New CVE Received by [email protected]
Mar. 03, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-79 Added Reference https://github.com/langgenius/dify/commit/ae17537470bba417a8971fff705dd82ecb043564 Added Reference https://github.com/langgenius/dify/pull/29811 Added Reference https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4