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medium advisory

Mozilla Firefox and Thunderbird WebCodecs Boundary Condition Vulnerability (CVE-2026-4695)

An incorrect boundary condition in the Audio/Video Web Codecs component in Mozilla Firefox and Thunderbird (CVE-2026-4695) could lead to a denial-of-service (DoS) condition due to a vulnerability that affects Firefox < 149, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

CVE-2026-4695 describes a vulnerability affecting Mozilla Firefox and Thunderbird related to incorrect boundary conditions in the Audio/Video Web Codecs component. This flaw impacts Firefox versions prior to 149, Firefox ESR versions prior to 140.9, Thunderbird versions prior to 149, and Thunderbird ESR versions prior to 140.9. An attacker could potentially exploit this vulnerability to cause a denial-of-service condition, impacting the availability of the application. This vulnerability was…

Detection coverage 2

Detect Firefox Crash Due to WebCodecs

medium

Detects Firefox crashes potentially related to WebCodecs vulnerabilities by monitoring for crash reports with WebCodecs-related modules.

sigma tactics: availability techniques: T1499.004 sources: process_creation, windows

Detect Thunderbird Crash Due to WebCodecs

medium

Detects Thunderbird crashes potentially related to WebCodecs vulnerabilities by monitoring for crash reports with WebCodecs-related modules.

sigma tactics: availability techniques: T1499.004 sources: process_creation, windows

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