CVE-2026-41159: Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts

Q: How do I fix CVE-2026-41159?

mermaid: upgrade to 10.9.6, 11.15.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-41159 being exploited?

CVE-2026-41159 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-41159 affect?

CVE-2026-41159 affects mermaid. Severity is medium (CVSS 5.3). 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 f

Q: How urgent is CVE-2026-41159?

Priority 34/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-41159 is a medium-severity flaw (CVSS 5.3) affecting mermaid. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ele

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-05-29
Last modified	2026-07-21

Publisher (CNA): GitHub, Inc. · Vendor: mermaid project

Last updated 2026-07-21 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-29 15:16 UTCPublished CVE record published
2026-07-21 12:10 UTCUpdated Record last modified

mermaid project mermaid UPGRADE

Affected: < 10.9.6 · >= 11.0.0 and < 11.15.0

Fixed in: 10.9.6, 11.15.0

Safe to downgrade to: a release before 11.0.0

1. Check installed version

npm ls mermaid

2. UPGRADE to 10.9.6

npm install mermaid@">=10.9.6"

3. If no update is available yet, DOWNGRADE to a release before 11.0.0

npm view mermaid versions npm install mermaid@"<11.0.0"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-41159?

mermaid: upgrade to 10.9.6, 11.15.0. Exact commands for each OS are on this page.

Is CVE-2026-41159 being exploited?

CVE-2026-41159 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-41159 affect?

CVE-2026-41159 affects mermaid. Severity is medium (CVSS 5.3). 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 f

How urgent is CVE-2026-41159?

Priority 34/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-41150 MEDIUM 5.3 UPGRADE Mermaid is a JavaScript tool that uses Markdown-inspired text to create and modify diagrams and charts

References

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