CVE-2022-40958: Mozilla Firefox

Medium severity, CVSS 6.5. EPSS: 1.1% chance of exploitation in the next 30 days.

By injecting a cookie with certain special characters, an attacker on a shared subdomain which is not a secure context could set and thus overwrite cookies from a secure context, leading to session fixation and other attacks. This vulnerability affects Firefox ESR < 102.3, Thunderbird < 102.3, and Firefox < 105.

Affected products

• Mozilla Firefox: before 105.0 (fixed in 105.0)
• Mozilla Firefox ESR: before 102.3 (fixed in 102.3)
• Mozilla Thunderbird: before 102.3 (fixed in 102.3)

Published 2022-12-22. Last modified 2026-06-17.