CVE-2022-26387: Mozilla Firefox

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 30 days.

When installing an add-on, Firefox verified the signature before prompting the user; but while the user was confirming the prompt, the underlying add-on file could have been modified and Firefox would not have noticed. This vulnerability affects Firefox < 98, Firefox ESR < 91.7, and Thunderbird < 91.7.

Affected products

• Mozilla Firefox: before 98.0 (fixed in 98.0)
• Mozilla Firefox ESR: before 91.7 (fixed in 91.7)
• Mozilla Thunderbird: before 91.7 (fixed in 91.7)

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