How severe is GHSA-ghcm-xqfw-q4vr?

No CVSS score has been assigned to GHSA-ghcm-xqfw-q4vr yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-ghcm-xqfw-q4vr?

GHSA-ghcm-xqfw-q4vr affects the following packages: mermaid (npm), mermaid (npm). Ecosystems affected: npm.

How do I fix GHSA-ghcm-xqfw-q4vr?

Update mermaid to 11.15.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ghcm-xqfw-q4vr is resolved across your whole dependency graph.

How do I detect GHSA-ghcm-xqfw-q4vr in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mermaid, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-ghcm-xqfw-q4vr if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is GHSA-ghcm-xqfw-q4vr actively exploited in the wild?

No public exploit code has been indexed for GHSA-ghcm-xqfw-q4vr yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-ghcm-xqfw-q4vr?

GHSA-ghcm-xqfw-q4vr has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 35th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-ghcm-xqfw-q4vr?

GHSA-ghcm-xqfw-q4vr is classified as Code Injection (CWE-94). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-ghcm-xqfw-q4vr published, and has it been updated?

GHSA-ghcm-xqfw-q4vr was published on May 11, 2026 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

Mermaid: Improper sanitization of `classDef` in state diagrams leads to HTML injectionGHSA-ghcm-xqfw-q4vr

Fix: mermaid-js/mermaid@37ff937

GHSA-ghcm-xqfw-q4vr is a Code Injection vulnerability in mermaid. A fix is available for mermaid — see the affected versions and patch details below.

Also known asCVE-2026-41149

Published

May 11, 2026

Updated

Sep 10, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for GHSA-ghcm-xqfw-q4vr.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

2Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

mermaidnpm

26.0Mdownloads / week

Description

Impact

Under the default configuration, Mermaid state diagram's classDef allow DOM injection that escapes the SVG, although <script> tags are removed, preventing XSS.

Proof-of-concept

stateDiagram-v2
  classDef xss fill:red</style></svg><style>*{x:x;y:y;overflow:visible!important;contain:none!important;transform:none!important;filter:none!important;clip-path:none!important}</style><div style="x:x;y:y;color:red;font:5em/1 monospace;display:grid;place-items:center;z-index:2147483647;width:100vw;height:100vh;position:fixed;top:0;left:0;background:black">HACKED</div><svg><style>a:b
  [*] --> A:::xss

Patches

Workarounds

If you can not update to a patched version, setting "securityLevel": "sandbox" will prevent this, by rendering the mermaid diagram in a sandboxed <iframe>.

Credits

Thanks to @zsxsoft from @KeenSecurityLab for reporting this vulnerability.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`mermaid`	≥ 11.0.0-alpha.1&&< 11.15.0	11.15.0`npm install mermaid@11.15.0`
📦npm	`mermaid`	all versions	10.9.6`npm install mermaid@10.9.6`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mermaid, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mermaid to 11.15.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-ghcm-xqfw-q4vr is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This Moderate flaw in Mermaid, a JavaScript diagramming tool, allows for HTML injection through specially crafted state diagrams. While script execution is prevented, an attacker could manipulate the rendered content, potentially leading to altered visual presentation or information disclosure. This issue primarily…

Workaround published by Red Hat

To mitigate this vulnerability, configure applications utilizing Mermaid to render diagrams within a sandboxed iframe by setting the `securityLevel` option to `sandbox`. This prevents the HTML injection from escaping the SVG context and affecting the parent document. Consult the documentation for the specific application integrating Mermaid for instructions on how to apply this configuration.

Source: Red Hat security advisory for GHSA-ghcm-xqfw-q4vr (CC BY 4.0)

Frequently Asked Questions

### Impact Under the default configuration, Mermaid state diagram's `classDef` allow DOM injection that escapes the SVG, although `<script>` tags are removed, preventing XSS. #### Proof-of-concept ``` stateDiagram-v2 classDef xss fill:red</style></svg><style>*{x:x;y:y;overflow:visible!important;contain:none!important;transform:none!important;filter:none!important;clip-path:none!important}</style><div style="x:x;y:y;color:red;font:5em/1 monospace;display:grid;place-items:center;z-index:2147483647;width:100vw;height:100vh;position:fixed;top:0;left:0;background:black">HACKED</div><svg><style

O3 Security · Impact-Aware SCA

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