Mozilla Firefox — CVE-2026-74936 (Critical)

Date Aug 18, 2026

Type Vendor advisory

Signal Critical vendor advisory

Vendor / Product Mozilla · Firefox

CVE CVE-2026-74936

Critical vendor advisory CVE-2026-74936

Summary

Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

Why it matters

This CVE carries a CRITICAL severity rating (CVSS 9.8) in Mozilla Firefox. Patch or mitigate promptly. EPSS percentile: 5%.

Operator check

Review CVE-2026-74936 in your asset inventory. Apply patches per vendor guidance and verify Firefox is not exposed. CVSS score: 9.8. EPSS probability: 0.2%; percentile: 5%.

Sources

NVD — CVE-2026-74936 Source reference Source reference

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

Get watched-vendor alerts Subscribe free Back to feed