Mermaid allows CSS injection applying to sibling elements of the diagram

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-50159
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-06 22:17:17 UTC
Updated2026-08-07 18:17:18 UTC
DescriptionMermaid 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.

Risk And Classification

Primary CVSS: v4.0 5.3 MEDIUM from [email protected]

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/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

EPSS: 0.005690000 probability, percentile 0.439960000 (date 2026-08-10)

Problem Types: CWE-94 | CWE-94 CWE-94: Improper Control of Generation of Code ('Code Injection')

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L/E:X/C...
4.0CNADECLARED5.3MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
None
Integrity
Low
Availability
None
Sub Conf.
Low
Sub Integrity
Low
Sub Availability
Low

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/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mermaid-js Mermaid affected < 10.9.8 Not specified
CNA Mermaid-js Mermaid affected >= 11.0.0-alpha.1, < 11.16.1 Not specified

References

ReferenceSourceLinkTags
github.com/mermaid-js/mermaid/commit/12d472c9ed43f94814b110da8d7a9ae6dd5... [email protected] github.com
github.com/mermaid-js/mermaid/releases/tag/[email protected] [email protected] github.com
github.com/mermaid-js/mermaid/security/advisories/GHSA-6x64-9x62-f2gx [email protected] github.com
github.com/mermaid-js/mermaid/releases/tag/v10.9.8 [email protected] github.com
github.com/mermaid-js/mermaid/pull/8022 [email protected] github.com
github.com/mermaid-js/mermaid/commit/7e83f1533318b307764d961906a73377266... [email protected] github.com
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