Description
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 products
mozilla: firefox; mozilla: thunderbird
References5
- www.mozilla.org/security/advisories/mfsa2026-74/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-77/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-78/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-80/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=2060048 Permissions Required
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H - EPSS — exploit probability
- 1% percentile: 47 · as of 11 November 2026
- CWE
- CWE-200
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