A vulnerability while parsing "application/http-index-format" format content where uninitialized values are used to create an array. This could allow the reading of uninitialized memory into the arrays affected. This vulnerability affects Thunderbird < 52.1, Firefox ESR < 45.9, Firefox ESR < 52.1, and Firefox < 53.
Severity
CVSS 3.0
7.5 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
2.6% chance of exploitation in the next 30 days; higher than 85% of CVEs (scores of 2026-10-31)