Critical severity9.1NVD Advisory· Published Aug 18, 2026· Updated Aug 25, 2026
CVE-2026-74986
CVE-2026-74986
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
7- Range: >=154, >=153.1
- osv-coords6 versionspkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/MozillaFirefox&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/firefox-esr&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/mozilla-nspr&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/mozilla-nss&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/rust-cbindgen&distro=openSUSE%20Leap%2016.0
< 153.1.0-160000.1.2+ 5 more
- (no CPE)range: < 153.1.0-160000.1.2
- (no CPE)range: < 154.0-1.1
- (no CPE)range: < 153.1.0-1.1
- (no CPE)range: < 4.39-160000.1.1
- (no CPE)range: < 3.125-160000.1.1
- (no CPE)range: < 0.29.4+git0-160000.1.1
Patches
Vulnerability mechanics
References
5- www.mozilla.org/security/advisories/mfsa2026-74/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-77/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-78/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-80/nvdVendor Advisory
- bugzilla.mozilla.org/show_bug.cginvdPermissions Required
News mentions
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