CVE-2026-0877

high

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.

References

https://www.mozilla.org/security/advisories/mfsa2026-05/

https://www.mozilla.org/security/advisories/mfsa2026-04/

https://www.mozilla.org/security/advisories/mfsa2026-03/

https://www.mozilla.org/security/advisories/mfsa2026-02/

https://www.mozilla.org/security/advisories/mfsa2026-01/

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-0877.json

https://bugzilla.redhat.com/show_bug.cgi?id=2428969

https://bugzilla.mozilla.org/show_bug.cgi?id=1999257

https://access.redhat.com/security/cve/CVE-2026-0877

https://access.redhat.com/errata/RHSA-2026:2286

https://access.redhat.com/errata/RHSA-2026:2271

https://access.redhat.com/errata/RHSA-2026:2231

https://access.redhat.com/errata/RHSA-2026:2220

https://access.redhat.com/errata/RHSA-2026:2074

https://access.redhat.com/errata/RHSA-2026:2073

https://access.redhat.com/errata/RHSA-2026:2070

https://access.redhat.com/errata/RHSA-2026:2069

https://access.redhat.com/errata/RHSA-2026:2047

https://access.redhat.com/errata/RHSA-2026:2044

https://access.redhat.com/errata/RHSA-2026:2043

https://access.redhat.com/errata/RHSA-2026:2041

https://access.redhat.com/errata/RHSA-2026:1487

https://access.redhat.com/errata/RHSA-2026:1471

https://access.redhat.com/errata/RHSA-2026:1462

https://access.redhat.com/errata/RHSA-2026:1461

https://access.redhat.com/errata/RHSA-2026:1415

https://access.redhat.com/errata/RHSA-2026:1414

https://access.redhat.com/errata/RHSA-2026:1413

https://access.redhat.com/errata/RHSA-2026:1320

https://access.redhat.com/errata/RHSA-2026:0924

https://access.redhat.com/errata/RHSA-2026:0694

https://access.redhat.com/errata/RHSA-2026:0667

Details

Source: Mitre, NVD

Published: 2026-01-13

Updated: 2026-06-30

Risk Information

CVSS v2

Base Score: 9.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:N

Severity: High

CVSS v3

Base Score: 7.5

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

Severity: High

EPSS

EPSS: 0.0004