Medium (5.9). EPSS 2.4% chance of exploitation in the next 30 days.
An existing mitigation of timing side-channel attacks is insufficient in some circumstances. This issue is addressed in Network Security Services (NSS) 3.26.1. This vulnerability affects Thunderbird < 45.5, Firefox ESR < 45.5, and Firefox < 50.
Severity
CVSS 3.0
5.9 medium
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
2.4% chance of exploitation in the next 30 days; higher than 83% of CVEs (scores of 2026-10-31)