CVE-2026-12299: JIT miscompilation in the DOM: Core & HTML component

Published Jun 16, 2026
·
Updated

JIT miscompilation in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

Affected Software

10 affected componentsFixes available
Mozilla Firefox ESR<140.12
140.12
Mozilla Firefox<152
152
Mozilla Firefox ESR<115.37
115.37
Mozilla Thunderbird<140.12
140.12
Mozilla Thunderbird<152
152
Mozilla Firefox<115.37.0
Mozilla Firefox<152.0
Mozilla Firefox>=140.0<140.12.0
Mozilla Thunderbird<152.0.0
Mozilla Thunderbird>=140.0<140.12.0

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 140.12
  2. Upgrade

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

    Fixed in 152
  3. Upgrade

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

    Fixed in 115.37
  4. Upgrade

    Upgrade Mozilla Firefox / Firefox ESR / Thunderbird to a version that resolves this vulnerability.

    Fixed in 152
  5. Upgrade

    Upgrade Mozilla Firefox ESR / Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.12
  6. Upgrade

    Upgrade Mozilla Firefox ESR / Thunderbird to a version that resolves this vulnerability.

    Fixed in 115.37

Event History

Jun 16, 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·11:52 AM
Data Sourced
via MITRE·11:52 AM
Description
Data Sourced
via NVD·01:16 PM
DescriptionSeverityWeaknessAffected Software
Data Sourced
via Red Hat·02:01 PM
DescriptionSeverityAffected Software
May 20, 58464
Event
via NVD·04:12 PM

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

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Frequently Asked Questions

1

What is the severity of CVE-2026-12299?

The severity of CVE-2026-12299 is medium with a CVSS score of 5.4.

2

How do I fix CVE-2026-12299?

To fix CVE-2026-12299, users should update to Firefox version 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, or Thunderbird 140.12.

3

What components are affected by CVE-2026-12299?

CVE-2026-12299 affects the JIT compilation process in the DOM: Core & HTML component.

4

Is CVE-2026-12299 present in older versions of Mozilla software?

Yes, CVE-2026-12299 is present in older versions of Mozilla Firefox and Thunderbird prior to the fixed releases.

5

What type of vulnerability is CVE-2026-12299?

CVE-2026-12299 is categorized as a JIT miscompilation vulnerability.

Company

Resources

Contact

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