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Fencer Intel
high 8.1

CVE-2026-0877 json

Mitigation bypass in the DOM: Security component

published 9mo ago modified 3mo ago also EUVD-2026-2339

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:140.7.0-1.el10_1
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:140.7.0-1.el10_0
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:140.7.0-1.el7_9
  • Red Hat Red Hat Enterprise Linux 8 0:140.7.0-1.el8_10
  • Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support 0:140.7.0-1.el8_2
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:140.7.0-1.el8_4
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:140.7.0-1.el8_4
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:140.7.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service 0:140.7.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 0:140.7.0-1.el8_6
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:140.7.0-1.el8_8
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:140.7.0-1.el8_8
  • Red Hat Red Hat Enterprise Linux 9 0:140.7.0-1.el9_7
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:140.7.0-1.el9_0
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:140.7.0-1.el9_2
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support 0:140.7.0-1.el9_4
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:140.7.0-1.el9_6, 0:140.7.0-2.el9_6
  • firefox-esr Debian 12 140.7.0esr-1~deb12u1
  • firefox-esr Debian 13 140.7.0esr-1~deb13u1
  • firefox-esr Debian 14 140.7.0esr-1
  • thunderbird Debian 12 1:140.7.0esr-1~deb12u1
  • thunderbird Debian 13 1:140.7.0esr-1~deb13u1
  • thunderbird Debian 14 1:140.7.0esr-1

debian advisories DEBIAN-CVE-2026-0877

  • thunderbird Ubuntu 22.04 LTS 1:140.7.1+build1-0ubuntu0.22.04.1

ubuntu advisories UBUNTU-CVE-2026-0877

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • firefox RHEL 10.1 140.7.0-1.el10_1
  • thunderbird RHEL 10.1 140.7.0-1.el10_1
  • thunderbird RHEL 8 140.7.0-1.el8_10
  • thunderbird RHEL 9 140.7.0-1.el9_7
  • firefox RHEL 9 140.7.0-1.el9_7
  • firefox-x11 RHEL 9 140.7.0-1.el9_7
  • firefox RHEL 8 140.7.0-1.el8_10
  • firefox enterprise linux eus 10.0 140.7.0-1.el10_0

red hat advisories RHSA-2026:2271RHSA-2026:2286RHSA-2026:2231RHSA-2026:2220RHSA-2026:2074RHSA-2026:2070

  • MozillaFirefox SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +9 more 140.7.0-150200.152.216.1
  • MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7, openSUSE Leap 15.6 140.7.0-150200.8.251.1
  • MozillaFirefox SLES for SAP applications 16.0, SLES 16.0 140.7.0-160000.1.1
  • MozillaFirefox SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 140.7.0-112.295.1

suse advisories SUSE-SU-2026:0260-1SUSE-SU-2026:0153-1SUSE-SU-2026:20086-1SUSE-SU-2026:0122-1

  • MozillaThunderbird openSUSE Leap 16.0 140.8.1-bp160.1.1
  • MozillaThunderbird openSUSE Tumbleweed 140.7.0-1.1
  • MozillaFirefox openSUSE Leap 16.0 140.7.0-160000.1.1
  • MozillaFirefox openSUSE Tumbleweed 147.0-1.1
  • firefox-esr openSUSE Tumbleweed 140.7.0-1.1

opensuse advisories openSUSE-SU-2026:20391-1openSUSE-SU-2026:10058-1openSUSE-SU-2026:20041-1openSUSE-SU-2026:10046-1openSUSE-SU-2026:10037-1

  • thunderbird AlmaLinux 8 140.7.0-1.el8_10.alma.1
  • firefox AlmaLinux 10 140.7.0-1.el10_1
  • thunderbird AlmaLinux 10 140.7.0-1.el10_1.alma.1
  • thunderbird AlmaLinux 9 140.7.0-1.el9_7.alma.1
  • firefox AlmaLinux 8 140.7.0-1.el8_10.alma.1
  • firefox AlmaLinux 9 140.7.0-1.el9_7.alma.1
  • firefox-x11 AlmaLinux 9 140.7.0-1.el9_7.alma.1

almalinux advisories ALSA-2026:2220ALSA-2026:2271ALSA-2026:2286ALSA-2026:0924ALSA-2026:0667ALSA-2026:0694

  • thunderbird Rocky Linux 8 140.7.0-1.el8_10
  • thunderbird Rocky Linux 9 140.7.0-1.el9_7
  • firefox Rocky Linux 9 140.7.0-1.el9_7
  • firefox Rocky Linux 8 140.7.0-1.el8_10

rocky linux advisories RLSA-2026:2220RLSA-2026:0924RLSA-2026:0694RLSA-2026:0667

Is CVE-2026-0877 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-0877 updated cvss 7.5

firefox: thunderbird: Mitigation bypass in the DOM: Security component

  • Red Hat Enterprise Linux 6 firefox, thunderbird Red Hat Enterprise Linux 7 thunderbird
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 10 rhel8/flatpak-runtime, rhel10/firefox-flatpak
    affected: workaround, no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) firefox 140.7.0-1.el8_10, thunderbird 140.7.0-1.el8_10
    fixed: vendor fix RHSA-2026:0667
  • Red Hat Enterprise Linux AppStream (v. 9) firefox 140.7.0-1.el9_7, firefox-x11 140.7.0-1.el9_7, thunderbird 140.7.0-1.el9_7
    fixed: vendor fix RHSA-2026:0694
  • Red Hat Enterprise Linux AppStream (v. 10) firefox 140.7.0-1.el10_1, thunderbird 140.7.0-1.el10_1
    fixed: vendor fix RHSA-2026:2271
  • Red Hat Enterprise Linux AppStream AUS (v. 8.2) firefox 140.7.0-1.el8_2, thunderbird 140.7.0-1.el8_2
    fixed: vendor fix RHSA-2026:2074
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) firefox 140.7.0-1.el8_4, thunderbird 140.7.0-1.el8_4
    fixed: vendor fix RHSA-2026:2073
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) firefox 140.7.0-1.el8_6, thunderbird 140.7.0-1.el8_6 Red Hat Enterprise Linux AppStream E4S (v.8.6) firefox 140.7.0-1.el8_6, thunderbird 140.7.0-1.el8_6
    fixed: vendor fix RHSA-2026:2070
show 10 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) firefox 140.7.0-1.el8_8, thunderbird 140.7.0-1.el8_8
    fixed: vendor fix RHSA-2026:2069
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) firefox 140.7.0-1.el9_0, thunderbird 140.7.0-1.el9_0
    fixed: vendor fix RHSA-2026:2047
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) firefox 140.7.0-1.el9_2, firefox-x11 140.7.0-1.el9_2, thunderbird 140.7.0-1.el9_2
    fixed: vendor fix RHSA-2026:2044
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) firefox 140.7.0-1.el10_0, thunderbird 140.7.0-1.el10_0
    fixed: vendor fix RHSA-2026:2271
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) firefox 140.7.0-1.el9_4, firefox-x11 140.7.0-1.el9_4, thunderbird 140.7.0-1.el9_4
    fixed: vendor fix RHSA-2026:2041
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) firefox 140.7.0-1.el9_6, firefox-x11 140.7.0-1.el9_6, thunderbird 140.7.0-2.el9_6
    fixed: vendor fix RHSA-2026:2043
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) firefox 140.7.0-1.el8_4, thunderbird 140.7.0-1.el8_4
    fixed: vendor fix RHSA-2026:2073
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) firefox 140.7.0-1.el8_6, thunderbird 140.7.0-1.el8_6
    fixed: vendor fix RHSA-2026:2070
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) firefox 140.7.0-1.el8_8, thunderbird 140.7.0-1.el8_8
    fixed: vendor fix RHSA-2026:2069
  • Red Hat Enterprise Linux Server (v. 7 ELS) firefox 140.7.0-1.el7_9
    fixed: vendor fix RHSA-2026:2231

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
9mo ago

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • Mozilla Firefox
  • Mozilla Thunderbird
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7

Classification

Weakness
  • CWE-693 Protection Mechanism Failure

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.