CVE-2026-26226

Description

beautiful-mermaid versions prior to 0.1.3 contain an SVG attribute injection issue that can lead to cross-site scripting (XSS) when rendering attacker-controlled Mermaid diagrams. User-controlled values from Mermaid style and classDef directives are interpolated into SVG attribute values without proper escaping, allowing crafted input to break out of an attribute context and inject arbitrary SVG elements/attributes into the rendered output. When the generated SVG is embedded in a web page, this can result in script execution in the context of the embedding origin.

PUBLISHED Reserved 2026-02-11 | Published 2026-02-13 | Updated 2026-02-13 | Assigner VulnCheck

Problem types

CWE-79 Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting')

Product status

Credits

Neo by ProjectDiscovery (https://neo.projectdiscovery.io) finder

References

github.com/lukilabs/beautiful-mermaid/releases/tag/v0.1.3 release-notes patch

github.com/lukilabs/beautiful-mermaid/pull/8 issue-tracking

neo.projectdiscovery.io/...71dc7-a8eb-417e-b8b4-666644796c1e technical-description exploit

www.vulncheck.com/...autiful-mermaid-svg-attribute-injection third-party-advisory

cve.org (CVE-2026-26226)

nvd.nist.gov (CVE-2026-26226)

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