Prototype pollution vulnerability found in Mermaid's bundled version of DOMPurify

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.0 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

The following bundled files within the Mermaid NPM package contain a bundled version of DOMPurify that is vulnerable to https://github.com/cure53/DOMPurify/security/advisories/GHSA-mmhx-hmjr-r674, potentially resulting in an XSS attack. This affects the built: - dist/mermaid.min.js - dist/mermaid.js - dist/mermaid.esm.mjs - dist/mermaid.esm.min.mjs This will also affect users that use the above files via a CDN link, e.g. https://cdn.jsdelivr.net/npm/mermaid@10.9.2/dist/mermaid.min.js Users that use the default NPM export of mermaid, e.g. import mermaid from 'mermaid', or the dist/mermaid.core.mjs file, do not use this bundled version of DOMPurify, and can easily update using their package manager with something like npm audit fix. Patches - develop branch: 6c785c93166c151d27d328ddf68a13d9d65adc00 - backport to v10: 92a07ffe40aab2769dd1c3431b4eb5beac282b34

Published by the source

22 Oct 2024, 18:17 UTC

Last modified by the source

23 Oct 2024, 16:58 UTC

Source last checked

26 Oct 2026, 12:31 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-m4gq-x24j-jpmf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-m4gq-x24j-jpmf

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-m4gq-x24j-jpmf

Advisory: Prototype pollution vulnerability found in Mermaid's bundled version of DOMPurify
IDs: GHSA-m4gq-x24j-jpmf
Record: https://patchnext.com/advisories/ghsa-m4gq-x24j-jpmf (revision 2, source checked 26 Oct 2026, 12:31 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mermaid 10.9.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm mermaid: affected <= 10.9.2; fixed in 10.9.3

## Suggested inspection (read-only)
- `npm ls mermaid --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mermaid.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-m4gq-x24j-jpmf (OSV record GHSA-m4gq-x24j-jpmf lists affected ranges: npm mermaid >=0 <10.9.3 (fixed))
- Verified: https://github.com/advisories/GHSA-m4gq-x24j-jpmf (GitHub-reviewed advisory GHSA-m4gq-x24j-jpmf lists affected ranges: npm mermaid >=0 <=10.9.2)

Commands are suggestions: review each one before running it.