CVE-2026-2767: Use-after-free in the JavaScript: WebAssembly component

Published Feb 24, 2026
·
Updated

Use-after-free in the JavaScript: WebAssembly component. This vulnerability affects Firefox < 148 and Firefox ESR < 140.8.

Other sources

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

— MITRE

Affected Software

8 affected componentsFixes available
Mozilla Firefox<148
148
Mozilla Firefox ESR<140.8
140.8
Mozilla Thunderbird<148
148
Mozilla Thunderbird<140.8
140.8
Mozilla Firefox<140.8.0
Mozilla Firefox<148.0
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 Firefox to a version that resolves this vulnerability.

    Fixed in 148
  4. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.8
  5. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 148
  6. 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·02:05 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software
Jan 4, 58137
Event
via FIRST·09:21 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-2026-2767?

CVE-2026-2767 has a severity rating of critical with a score of 9.8 according to the CVSS 3.1 metrics.

2

How do I fix CVE-2026-2767?

To fix CVE-2026-2767, update to Firefox version 148 or later, Firefox ESR version 140.8 or later, or Thunderbird version 148 or later.

3

What components are affected by CVE-2026-2767?

CVE-2026-2767 affects the JavaScript: WebAssembly component in Firefox and Thunderbird.

4

What types of attacks could exploit CVE-2026-2767?

CVE-2026-2767 could be exploited through use-after-free vulnerabilities, potentially leading to memory corruption.

5

What versions of Firefox are vulnerable to CVE-2026-2767?

Firefox versions earlier than 148 and Firefox ESR versions earlier than 140.8 are vulnerable to CVE-2026-2767.

Company

Resources

Contact

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