CVE-2022-26387

Name: CVE-2022-26387
Creator: NVD / NIST
Published: 2022-12-22T20:15:22.34+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.66%

Last modified Jun 17, 2026

CVE-2022-26387 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 0.66% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS Probability

0.66%

46.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 98.0
Mozilla	Firefox Esr	< 91.7
Mozilla	Thunderbird	< 91.7

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1752979Exploit, Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-10/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-11/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-12/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1752979Exploit, Issue Tracking, Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-10/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-11/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-12/Vendor Advisory

Timeline

Published: Dec 22, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-26387?

How severe is CVE-2022-26387?

CVE-2022-26387 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.66% probability of exploitation in the next 30 days.

How do I fix CVE-2022-26387?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2022-26387?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST