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CVE-2026-16387criticalCWE-200CWE-284CWE-346

Site isolation issue in the Networking component

28Vexday Risk Score

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

ssvc Trackcvss 9.8epss 0.2%
exploitation probability
0.2%top 89% of all CVEs
observed exploitation
nono source reports it
Site isolation issue in the Networking component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H