High (8.8). EPSS 1.6% chance of exploitation in the next 30 days.
An attacker could have caused 4 bytes of HMAC output to be written past the end of a buffer stored on the stack. This could be used by an attacker to execute arbitrary code or more likely lead to a crash. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.
Severity
CVSS 3.1
8.8 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EPSS
1.6% chance of exploitation in the next 30 days; higher than 76% of CVEs (scores of 2026-10-31)