CVE-2026-84119: Sandbox escape due to use-after-free in the DOM: Navigation component

Published Sep 1, 2026
·
Updated

Sandbox escape due to use-after-free in the DOM: Navigation component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Affected Software

14 affected componentsFixes available
Mozilla Firefox<155
155
Mozilla Firefox ESR<140.15
140.15
Mozilla Firefox ESR<115.40
115.40
Mozilla Firefox ESR<153.2
153.2
Mozilla Thunderbird<155
155
Mozilla Thunderbird<140.15
140.15
Mozilla Thunderbird<153.2
153.2
Mozilla Firefox<115.40.0
Mozilla Firefox>=116.0<140.15.0
Mozilla Firefox>=141.0.0<153.2.0
Mozilla Firefox>=154.0.0<155.0.0
Mozilla Thunderbird<140.15.0
Mozilla Thunderbird>=141.0<153.2.0
Mozilla Thunderbird>=154.0<155.0

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 155
  2. Upgrade

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

    Fixed in 140.15
  3. Upgrade

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

    Fixed in 115.40
  4. Upgrade

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

    Fixed in 153.2
  5. Upgrade

    Upgrade Mozilla Firefox to a version that resolves this vulnerability.

    Fixed in 155
  6. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.40
  7. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.15
  8. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 153.2
  9. Upgrade

    Upgrade Mozilla Thunderbird to a version that resolves this vulnerability.

    Fixed in 155
  10. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.15
  11. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 153.2

Event History

Sep 1, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Updated
via Mozilla·12:00 AM
Affected Software
CVE Published
via MITRE·12:18 PM
Data Sourced
via MITRE·12:18 PM
Description
Data Sourced
via NVD·01:20 PM
DescriptionSeverityWeaknessAffected Software

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which Firefox releases contain the fix?

The issue was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2.

Company

Resources

Contact

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