DOMPurify before 3.4.7 (affected versions <= 3.4.5) passes direct references to the module-level DEFAULTALLOWEDTAGS and DEFAULTALLOWEDATTR sets to the uponSanitizeElement and uponSanitizeAttribute hooks via data.allowedTags / data.allowedAttributes when sanitize is called without an explicit cfg.ALLOWEDTAGS / cfg.ALLOWEDATTR array. A hook that mutates these fields permanently widens the default allow-lists for the lifetime of the DOMPurify instance, so all subsequent default-config sanitize calls inherit the widened defaults and attacker payloads using the poisoned tag/attribute name survive sanitization. removeAllHooks(), clearConfig(), and passing a fresh cfg do not recover the state; only constructing a new DOMPurify instance does.
{
"cna_assigner": "VulnCheck",
"cwe_ids": [
"CWE-501"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/65xxx/CVE-2026-65902.json"
}