VULNERABILITY INTELLIGENCE

CVE-2021-29946

CVSS score8.8 HIGH

EPSS probability1.30%

CISA KEVNot currently listed

Published2021-06-24

Last modified2026-06-17

Description

Ports that were written as an integer overflow above the bounds of a 16-bit integer could have bypassed port blocking restrictions when used in the Alt-Svc header. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.