GHSA-cj63-jhhr-wcxv

When USE_PROFILES is enabled, DOMPurify rebuilds ALLOWED_ATTR as a plain array before populating it with the requested allowlists. Because the sanitizer still looks up attributes via ALLOWED_ATTR[lcName], any Array.prototype property that is polluted also counts as an allowlisted attribute. An attacker who can set Array.prototype.onclick = true (or a runtime already subject to prototype pollution) can thus force DOMPurify to keep event handlers such as onclick even when they are normally forbidden. The provided PoC sanitizes <img onclick=...> with USE_PROFILES and adds the sanitized output to the DOM; the polluted prototype allows the event handler to survive and execute, turning what should be a blocklist into a silent XSS vector.

Impact

Prototype pollution makes DOMPurify accept dangerous event handler attributes, which bypasses the sanitizer and results in DOM-based XSS once the sanitized markup is rendered.

Credits

Identified by Cantina’s Apex (https://www.cantina.security).

Database specific

{
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T03:45:08Z",
    "cwe_ids": [
        "CWE-1321"
    ],
    "severity": "MODERATE",
    "nvd_published_at": null
}

References

Affected packages

npm / dompurify

Package

Name: dompurify; View open source insights on deps.dev
Purl: pkg:npm/dompurify

Affected ranges

Type: SEMVER
Events: Introduced

0Unknown introduced version / All previous versions are affected

Fixed

3.3.2

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-cj63-jhhr-wcxv/GHSA-cj63-jhhr-wcxv.json"

last_known_affected_version_range

"<= 3.3.1"