mermaid-js Mermaid up to 10.9.7/11.16.0 injection

Summaryinfo

A vulnerability has been found in mermaid-js Mermaid up to 10.9.7/11.16.0 and classified as critical. This issue affects some unknown processing. The manipulation leads to injection. This vulnerability is listed as CVE-2026-50159. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in mermaid-js Mermaid up to 10.9.7/11.16.0 and classified as critical. This issue affects an unknown part. The manipulation with an unknown input leads to a injection vulnerability. Using CWE to declare the problem leads to CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-50159 since 06/03/2026. The exploitation is known to be easy. The attack may be initiated remotely. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1055 for this issue.

Upgrading to version 10.9.8 or 11.16.1 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

• mermaid-js

Name

• Mermaid

Version

• 10.9.0
• 10.9.1
• 10.9.2
• 10.9.3
• 10.9.4
• 10.9.5
• 10.9.6
• 10.9.7
• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.5
• 11.6
• 11.7
• 11.8
• 11.9
• 11.10
• 11.11
• 11.12
• 11.13
• 11.14
• 11.15
• 11.16.0

Website

• Product: https://github.com/mermaid-js/mermaid/

CPE 2.3info

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CPE 2.2info

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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