Mitigation Bypass in Cache API of Firefox by Mozilla
CVE-2026-74959

Currently unrated

Key Information:

Vendor: Mozilla
Status: Firefox
Vendor: CVE Published:; 18 August 2026

What is CVE-2026-74959?

A mitigation bypass vulnerability impacting the Cache API of Firefox was identified, which was addressed in recent updates. This flaw could allow unintended access or manipulation of cached data, affecting the integrity of web applications relying on proper cache management. Users are advised to update to Firefox 154, Firefox ESR 140.14, or Firefox ESR 153.1 to ensure robust protection against potential exploits.

Affected Version(s)

Firefox 140.14

Firefox 153.1

Firefox 154

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2047853

https://www.mozilla.org/security/advisories/mfsa2026-74/

https://www.mozilla.org/security/advisories/mfsa2026-76/

Download the Critical Vulnerability Management Cheat Sheet

Timeline

Vulnerability published
Aug 18, 2026
Vulnerability Reserved
Aug 17, 2026

Credit

David Bors at Snyk Security Labs

CVE-2026-74959 Data

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