CVE-2026-74956

9.1 criticalEPSS 0.5%

Critical (9.1) in mozilla. EPSS 0.5% chance of exploitation in the next 30 days.

Same-origin policy bypass in the DOM: Service Workers component. This vulnerability was fixed in Firefox 154, Firefox ESR 153.1, Thunderbird 154, and Thunderbird 153.1.

Severity

CVSS 3.1

9.1 critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS: 0.5% chance of exploitation in the next 30 days; higher than 42% of CVEs (scores of 2026-10-31)
CWE: CWE-843
Published: 2026-08-18
Modified: 2026-08-19
Record from: the NVD, synced 2026-10-19

Affected

mozilla:firefox
mozilla:thunderbird

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2032406
https://www.mozilla.org/security/advisories/mfsa2026-74/
https://www.mozilla.org/security/advisories/mfsa2026-77/
https://www.mozilla.org/security/advisories/mfsa2026-78/
https://www.mozilla.org/security/advisories/mfsa2026-80/

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