CVE-2026-2763: Use-after-free in the JavaScript Engine component

Published Feb 24, 2026
·
Updated

Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.

Other sources

Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

— MITRE

Affected Software

10 affected componentsFixes available
Mozilla Firefox<148
148
Mozilla Firefox ESR<140.8
140.8
Mozilla Firefox ESR<115.33
115.33
Mozilla Thunderbird<148
148
Mozilla Thunderbird<140.8
140.8
Mozilla Firefox<115.33.0
Mozilla Firefox<148.0
Mozilla Firefox>=128.0<140.8.0
Mozilla Thunderbird<140.8.0
Mozilla Thunderbird<148.0

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 148
  2. Upgrade

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

    Fixed in 140.8
  3. Upgrade

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

    Fixed in 115.33
  4. Upgrade

    Upgrade Mozilla Firefox to a version that resolves this vulnerability.

    Fixed in 148
  5. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 115.33
  6. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.8
  7. Upgrade

    Upgrade Mozilla Thunderbird to a version that resolves this vulnerability.

    Fixed in 148
  8. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.8

Event History

Feb 24, 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·01:33 PM
Data Sourced
via MITRE·01:33 PM
Description
Data Sourced
via Red Hat·02:04 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software
Jan 4, 58137
Event
via FIRST·02:20 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-2026-2763?

CVE-2026-2763 has a critical severity rating of 9.8 according to CVSS 3.1.

2

Which software is affected by CVE-2026-2763?

CVE-2026-2763 affects Firefox versions earlier than 148, Firefox ESR versions earlier than 115.33 and 140.8, as well as Thunderbird version 148.

3

How do I fix CVE-2026-2763?

To fix CVE-2026-2763, update Firefox or Thunderbird to version 148 or later, and Firefox ESR to 115.33 or 140.8 or later.

4

What type of vulnerability is CVE-2026-2763?

CVE-2026-2763 is classified as a use-after-free vulnerability in the JavaScript Engine component.

5

What are the potential impacts of CVE-2026-2763?

Exploitation of CVE-2026-2763 could lead to critical security issues, including potential data corruption or arbitrary code execution.

Company

Resources

Contact

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