Mozilla Firefox before 26.0, Firefox ESR 24.x before 24.2, Thunderbird before 24.2, and SeaMonkey before 2.23 do not recognize a user's removal of trust from an EV X.509 certificate, which makes it easier for man-in-the-middle attackers to spoof SSL servers in opportunistic circumstances via a valid certificate that is unacceptable to the user.
Severity
CVSS 3.1
5.9 medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
EPSS
2.9% chance of exploitation in the next 30 days; higher than 86% of CVEs (scores of 2026-10-31)