CVE-2026-74962highCWE-346

CVE-2026-74962: high-severity vulnerability in Mozilla Firefox

Site isolation issue in the Networking: Cookies component

Published 18 Aug 2026 · Updated 19 Aug 2026

Follow this CVE + Monitor Firefox + Monitor Thunderbird

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 8.1epss 0.2%

Site isolation issue in the Networking: Cookies component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

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

Affected products

Mozilla · Firefox Mozilla · Thunderbird

Related CVEs — Mozilla Firefox

In the same product, most dangerous first.

CVE-2016-9079HIGHCVE-2016-9079EPSS 87.4%KEV CVE-2019-11708CRITICALCVE-2019-11708EPSS 55.9%KEV CVE-2019-17026HIGHCVE-2019-17026EPSS 46.3%KEV CVE-2019-11707HIGHCVE-2019-11707EPSS 38.0%KEV CVE-2024-9680CRITICALCVE-2024-9680EPSS 23.2%KEV CVE-2022-26485HIGHCVE-2022-26485EPSS 14.3%KEV

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2050425 https://www.mozilla.org/security/advisories/mfsa2026-74/https://www.mozilla.org/security/advisories/mfsa2026-76/https://www.mozilla.org/security/advisories/mfsa2026-77/https://www.mozilla.org/security/advisories/mfsa2026-78/https://www.mozilla.org/security/advisories/mfsa2026-79/https://www.mozilla.org/security/advisories/mfsa2026-80/