CVE-2026-0877: Mitigation bypass in the DOM: Security component

Published Jan 13, 2026
·
Updated

Mitigation bypass in the DOM: Security component. This vulnerability affects Firefox < 147, Firefox ESR < 115.32, and Firefox ESR < 140.7.

Other sources

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.

— Ubuntu

Affected Software

23 affected componentsFixes available
Mozilla Firefox ESR<115.32
115.32
Mozilla Thunderbird<147
147
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
ubuntu/mozjs52*
ubuntu/mozjs38*
ubuntu/mozjs68*
ubuntu/mozjs52*
ubuntu/mozjs102*
ubuntu/mozjs78*
ubuntu/mozjs91*
ubuntu/thunderbird<1:140.7.1+build1-0ubuntu0.22.04.1
1:140.7.1+build1-0ubuntu0.22.04.1
ubuntu/mozjs102*
ubuntu/mozjs115*
Mozilla Firefox<147
147
Mozilla Firefox ESR<140.7
140.7
Mozilla Thunderbird<140.7
140.7
debian/firefox
160.0-1
debian/firefox-esr
140.12.0esr-1~deb12u1153.7.0esr-1~deb12u1140.15.0esr-1~deb13u1153.6.0esr-1~deb13u1153.5.1esr-1153.7.0esr-1
debian/thunderbird
1:140.12.0esr-1~deb12u11:153.6.0esr-1~deb12u21:140.12.0esr-1~deb13u11:153.6.0esr-1~deb13u11:153.5.0esr-11:153.7.0esr-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 115.32
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 147
  3. Upgrade

    Upgrade ubuntu/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:140.7.1+build1-0ubuntu0.22.04.1
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 140.7
  5. Upgrade

    Upgrade debian/firefox to a version that resolves this vulnerability.

    Fixed in 160.0-1
  6. Upgrade

    Upgrade debian/firefox-esr to a version that resolves this vulnerability.

    Fixed in 140.12.0esr-1~deb12u1Fixed in 153.7.0esr-1~deb12u1Fixed in 140.15.0esr-1~deb13u1Fixed in 153.6.0esr-1~deb13u1Fixed in 153.5.1esr-1Fixed in 153.7.0esr-1
  7. Upgrade

    Upgrade debian/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:140.12.0esr-1~deb12u1Fixed in 1:153.6.0esr-1~deb12u2Fixed in 1:140.12.0esr-1~deb13u1Fixed in 1:153.6.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.7.0esr-1
  8. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 147
  9. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.32
  10. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.7
  11. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 147
  12. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.7

Event History

Jan 13, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Data Sourced
via Ubuntu·12:00 AM
RemedyDescriptionSeverityAffected Software
CVE Published
via MITRE·01:30 PM
Data Sourced
via MITRE·01:30 PM
Description
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
Data Sourced
via OSV·02:16 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

What is the severity of CVE-2026-0877?

The severity of CVE-2026-0877 is classified as high due to its potential for a mitigation bypass.

2

How do I fix CVE-2026-0877?

To fix CVE-2026-0877, update your Firefox browser to version 147 or later, or update your Firefox ESR to version 115.32 or later.

3

Which versions of Firefox are affected by CVE-2026-0877?

CVE-2026-0877 affects Firefox versions below 147, and Firefox ESR versions below 115.32 and 140.7.

4

Who is the vendor responsible for CVE-2026-0877?

The vendor responsible for CVE-2026-0877 is Mozilla.

5

What type of vulnerability is CVE-2026-0877?

CVE-2026-0877 is categorized as a mitigation bypass vulnerability specifically occurring within the DOM security component.

Company

Resources

Contact

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