Mozilla Firefox — CVE-2026-84141 (Critical)

Date Sep 1, 2026

Type Vendor advisory

Signal Critical vendor advisory

Vendor / Product Mozilla · Firefox

CVE CVE-2026-84141

Critical vendor advisory CVE-2026-84141

Summary

Integer overflow in the Graphics: ImageLib component. This vulnerability was fixed in Firefox 155, Firefox ESR 153.2, Thunderbird 155, and Thunderbird 153.2.

Why it matters

This CVE carries a CRITICAL severity rating (CVSS 9.8) in Mozilla Firefox. Patch or mitigate promptly. EPSS percentile: 4%.

Operator check

Review CVE-2026-84141 in your asset inventory. Apply patches per vendor guidance and verify Firefox is not exposed. CVSS score: 9.8. EPSS probability: 0.1%; percentile: 4%.

Sources

NVD — CVE-2026-84141 Source reference Source reference

PatchBrief uses public sources. It does not scan environments, verify exposure, or replace vendor guidance.

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