CVE-2023-23604: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 0.5% chance of exploitation in the next 30 days.

A duplicate `SystemPrincipal` object could be created when parsing a non-system html document via `DOMParser::ParseFromSafeString`. This could have lead to bypassing web security checks. This vulnerability affects Firefox < 109.

Affected products

• Mozilla Firefox: before 109.0 (fixed in 109.0)

Published 2023-06-02. Last modified 2026-06-17.