Description
Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.8 and 11.16.1, Mermaid is vulnerable to CSS injection via sibling combinator selectors generated from diagram-supplied class or id names. An attacker who can supply diagram text can inject arbitrary CSS into the rendered page, potentially altering the appearance or behavior of unrelated page elements. This issue is fixed in versions 10.9.8 and 11.16.1.
Published: 2026-08-06
Score: 5.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-6x64-9x62-f2gx Mermaid allows CSS injection applying to sibling elements of the diagram
History

Tue, 11 Aug 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-79
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N'}

threat_severity

Moderate


Fri, 07 Aug 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 07 Aug 2026 09:15:00 +0000

Type Values Removed Values Added
First Time appeared Mermaid Project
Mermaid Project mermaid
Vendors & Products Mermaid Project
Mermaid Project mermaid

Thu, 06 Aug 2026 22:15:00 +0000

Type Values Removed Values Added
Description Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts. Prior to 10.9.8 and 11.16.1, Mermaid is vulnerable to CSS injection via sibling combinator selectors generated from diagram-supplied class or id names. An attacker who can supply diagram text can inject arbitrary CSS into the rendered page, potentially altering the appearance or behavior of unrelated page elements. This issue is fixed in versions 10.9.8 and 11.16.1.
Title Mermaid allows CSS injection applying to sibling elements of the diagram
Weaknesses CWE-94
References
Metrics cvssV4_0

{'score': 5.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L'}


Subscriptions

Mermaid Project Mermaid
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-07T17:18:23.685Z

Reserved: 2026-06-03T20:54:20.432Z

Link: CVE-2026-50159

cve-icon Vulnrichment

Updated: 2026-08-07T17:18:10.914Z

cve-icon NVD

Status : Received

Published: 2026-08-06T22:17:17.180

Modified: 2026-08-07T18:17:18.830

Link: CVE-2026-50159

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-06T19:55:27Z

Links: CVE-2026-50159 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-11T01:45:06Z

Weaknesses