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VulnerabilityPublished Updated

CVE-2026-41159: mermaid · Code Injection

Affects mermaidSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 11.15.0 or 10.9.6 when convenient.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 4.0 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 11.15.0, 10.9.6
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 29 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade mermaid to 11.15.0 or 10.9.6; mermaid-js/mermaid to 10.9.6.

Affected software

ProductAffectedFixed in
mermaid-jsmermaidAffected
  • >=11.0.0-alpha.1 <11.15.0
Fixed in
  • 11.15.0
mermaid-jsmermaidAffected
  • <10.9.6
Fixed in
  • 10.9.6
npmmermaid-js/mermaidpkg:npm/mermaid-js/mermaidOther threatsAffected
  • <10.9.6
Fixed in
  • 10.9.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in mermaid versions 10.9.6 and 11.15.0. Users should upgrade to at least version 10.9.6 or later to remediate this issue. No other mitigation or temporary workaround is indicated in the available data.

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.

References

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