by Kastro
Paper/Archive/CVE-2026-74956

CVE-2026-74956

Mozilla Firefox — Same-origin policy bypass in the DOM: Service Workers component

EPSS 0.5%CVSS 9.1
critical.is priorityof 100
36
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 42.7.427 × 208.5No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
Firefoxsee advisory153.1CNA
Thunderbirdsee advisory153.1CNA

Scores by source

CISA ADP9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refbugzilla.mozilla.org/show_bug.cgi?id=2032406refmozilla.org/security/advisories/mfsa2026-74refmozilla.org/security/advisories/mfsa2026-77refmozilla.org/security/advisories/mfsa2026-78refmozilla.org/security/advisories/mfsa2026-80