Mozilla Releases Firefox 153 Fixing 63 Vulnerabilities Including Critical ESR Issues
Mozilla Foundation released Firefox 153 on July 21, 2026, addressing a total of 63 vulnerabilities tracked under CVE identifiers. The update also covers the Firefox ESR branch, where several flaws already had public exploit code available, earning a Critical severity rating. Among the High-severity issues resolved are same-origin policy bypasses in navigation handling such as CVE-2026-16349 and multiple memory-safety problems. The release further patches Use-After-Free vulnerabilities including CVE-2026-16362 and several sandbox escape flaws designated CVE-2026-16351, CVE-2026-16352, CVE-2026-16356, and CVE-2026-16367. Additional fixes cover boundary condition errors, integer overflows, miscompilation issues, privilege escalation vectors, and information disclosure problems. In total the advisory lists 20 High, 35 Moderate, and 8 Low severity vulnerabilities that have been mitigated.
Security NEXTJul 22, 2026Translated from Japanese