by Kastro
Paper/Archive/CVE-2026-74986

CVE-2026-74986

Mozilla Firefox — Site isolation issue in the CSS Parsing and Computation component

EPSS 0.6%CVSS 9.1
critical.is priorityof 100
37
CVSS 9.1 (ADP)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 46.3.463 × 209.3No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Site isolation issue in the CSS Parsing and Computation 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:N/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refbugzilla.mozilla.org/show_bug.cgi?id=2060048refmozilla.org/security/advisories/mfsa2026-74refmozilla.org/security/advisories/mfsa2026-77refmozilla.org/security/advisories/mfsa2026-78refmozilla.org/security/advisories/mfsa2026-80