CVE-2026-41159
Mermaid: Improper sanitization of configuration leads to CSS injection
Description
Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0, Mermaid's default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis's & (scope reference) handling. :not(&) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0.
INFO
Published Date :
May 29, 2026, 3:16 p.m.
Last Modified :
July 21, 2026, 12:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Mermaid to version 10.9.6 or later.
- Update Mermaid to version 11.15.0 or later.
- Review and sanitize CSS configurations within Mermaid.
Public PoC/Exploit Available at Github
CVE-2026-41159 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
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-2026-41159.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-41159 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-2026-41159
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).
None
Python JavaScript HTML C CSS PowerShell Batchfile Go Template
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-41159 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-41159 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.
-
CVE Translated by [email protected]
Jul. 21, 2026
Action Type Old Value New Value Added Translation Title: Mermaid de mermaid-js, Description: Mermaid es una herramienta de JavaScript que utiliza texto inspirado en Markdown para crear y modificar diagramas y gráficos. Antes de las versiones 10.9.6 y 11.15.0, la configuración predeterminada de Mermaid permite inyectar CSS que se aplica fuera del diagrama de Mermaid a través de las opciones de configuración fontFamily, themeCSS y altFontFamily. El CSS inyectado explota el manejo de & (referencia de ámbito) de stylis. :not(&) escapa el alcance automático #mermaid-xxx, aplicando estilos a todos los elementos de la página. Las reglas globales at-rules (@font-face, @keyframes, @counter-style) también son inyectables, ya que stylis las eleva al nivel superior. Esto permite la desfiguración de la página y la exfiltración de atributos del DOM a través de selectores CSS :has(). Esta vulnerabilidad se corrige en las versiones 10.9.6 y 11.15.0. -
CVE Modified by [email protected]
Jul. 01, 2026
Action Type Old Value New Value Added Reference https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aa Added Reference https://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76 Removed Reference https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aahttps://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76 Removed Reference Type https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aahttps://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76 Types: Patch -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'mermaid-js', 'product': 'mermaid', 'versions': [{'status': 'affected', 'version': '>= 11.0.0-alpha.1, < 11.15.0'}, {'status': 'affected', 'version': '< 10.9.6'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-41159', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-29T15:02:42.708368Z'} -
Initial Analysis by [email protected]
Jun. 01, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CPE Configuration OR *cpe:2.3:a:mermaid_project:mermaid:*:*:*:*:*:node.js:*:* versions up to (excluding) 10.9.6 *cpe:2.3:a:mermaid_project:mermaid:*:*:*:*:*:node.js:*:* versions from (including) 11.0.0 up to (excluding) 11.15.0 Added Reference Type GitHub, Inc.: https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aahttps://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/mermaid-js/mermaid/releases/tag/[email protected] Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p Types: Third Party Advisory -
New CVE Received by [email protected]
May. 29, 2026
Action Type Old Value New Value Added Description Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.6 and 11.15.0, Mermaid's default configuration allows injecting CSS that applies outside of the Mermaid diagram via the fontFamily, themeCSS, and altFontFamily configuration options. The injected CSS exploits stylis's & (scope reference) handling. :not(&) escapes the #mermaid-xxx automatic scoping, applying styles to all page elements. Global at-rules (@font-face, @keyframes, @counter-style) are also injectable as stylis hoists them to top level. This allows page defacement and DOM attribute exfiltration via CSS :has() selectors. This vulnerability is fixed in 10.9.6 and 11.15.0. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/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-94 Added Reference https://github.com/mermaid-js/mermaid/commit/64769738d5b59211e1decb471ffbaca8afec51aahttps://github.com/mermaid-js/mermaid/commit/a9d9f0d8eb790349121508688cd338253fd80d76 Added Reference https://github.com/mermaid-js/mermaid/releases/tag/[email protected] Added Reference https://github.com/mermaid-js/mermaid/releases/tag/v10.9.6 Added Reference https://github.com/mermaid-js/mermaid/security/advisories/GHSA-87f9-hvmw-gh4p