Mozilla Releases Firefox 153 Fixing 63 Vulnerabilities Including Critical ESR Issues
Mozilla Foundation has released Firefox 153 along with an updated Firefox ESR branch on July 21, 2026, resolving multiple security vulnerabilities.
The stable channel update addresses 63 CVEs and is rated High overall, while the ESR version fixes publicly exploitable flaws classified as Critical.
Twenty of the issues carry a High severity rating. These include a same-origin policy bypass in navigation handling tracked as CVE-2026-16349 and several memory-safety vulnerabilities.
Additional High-severity fixes cover a Use-After-Free flaw (CVE-2026-16362) and multiple sandbox escape vulnerabilities: CVE-2026-16351, CVE-2026-16352, CVE-2026-16356, and CVE-2026-16367.
The advisory also resolves boundary-condition errors, integer overflows, miscompilation problems, privilege-escalation vectors, and information-disclosure issues.
Thirty-five Moderate and eight Low severity vulnerabilities were likewise patched in the release.
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