CVE-2026-0877

Name: CVE-2026-0877
Creator: NVD / NIST
Published: 2026-01-13T14:16:38.27+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.1/10EPSS 0.31%

Last modified Jun 17, 2026

CVE-2026-0877 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 147, Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.. EPSS estimates a 0.31% chance of exploitation in the next 30 days.

Description

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 147, Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

Metrics

CVSS 3.1

8.1/10

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

EPSS Probability

0.31%

22.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-693

Affected Software

Vendor	Product	Versions
Mozilla	Firefox	< 115.32.0
Mozilla	Firefox	< 147.0
Mozilla	Firefox	>= 128.0, < 140.7.0
Mozilla	Thunderbird	< 140.7.0
Mozilla	Thunderbird	< 147.0

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1999257Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-01/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-02/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-03/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-04/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-05/Vendor Advisory

Timeline

Published: Jan 13, 2026
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2026-0877?

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 147, Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird 147, and Thunderbird 140.7.

How severe is CVE-2026-0877?

CVE-2026-0877 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.31% probability of exploitation in the next 30 days.

How do I fix CVE-2026-0877?

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-2026-0877?

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

Scan your code now

Source: NVD / NIST