CVE-2022-40958

Name: CVE-2022-40958
Creator: NVD / NIST
Published: 2022-12-22T20:15:39.08+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 1.10%

Last modified Jun 17, 2026

CVE-2022-40958 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 1.10% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

1.10%

61.6th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 105.0
Mozilla	Firefox Esr	< 102.3
Mozilla	Thunderbird	< 102.3

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1779993Issue Tracking, Permissions Required
https://www.mozilla.org/security/advisories/mfsa2022-40/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-41/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-42/Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1779993Issue Tracking, Permissions Required
https://www.mozilla.org/security/advisories/mfsa2022-40/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-41/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2022-42/Vendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2022-40958?

How severe is CVE-2022-40958?

CVE-2022-40958 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.10% probability of exploitation in the next 30 days.

How do I fix CVE-2022-40958?

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-2022-40958?

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

Scan your code now

Source: NVD / NIST