# CVE-2026-65902

## Summary

- **CVE ID:** CVE-2026-65902
- **Severity:** MEDIUM
- **CVSS Score:** 6.1 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N)
- **CWE:** CWE-501
- **Published:** Jul 23, 2026
- **Last Modified:** Jul 24, 2026

## Description

DOMPurify before 3.4.7 (affected versions <= 3.4.5) passes direct references to the module-level DEFAULT_ALLOWED_TAGS and DEFAULT_ALLOWED_ATTR sets to the uponSanitizeElement and uponSanitizeAttribute hooks via data.allowedTags / data.allowedAttributes when sanitize is called without an explicit cfg.ALLOWED_TAGS / cfg.ALLOWED_ATTR 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.

## Affected Products

- cure53 — DOMPurify (0)
- cure53 — DOMPurify (3.4.7)

## References

- [CNA](https://github.com/cure53/DOMPurify/security/advisories/GHSA-76mc-f452-cxcm)
- [CNA](https://github.com/cure53/DOMPurify/commit/7996f1dc78eb8b7922388aed75d94a9f8fad9a36)
- [CNA](https://www.vulncheck.com/advisories/dompurify-before-hook-mutation-pollution-via-allowedtags)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.24%
- **EPSS Percentile:** 14.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._