CVE-2026-6759: Use-after-free in the Widget: Cocoa component

Published Apr 21, 2026
·
Updated

Use-after-free in the Widget: Cocoa component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Affected Software

7 affected componentsFixes available
Mozilla Firefox ESR<140.10
140.10
Mozilla Firefox<150
150
Mozilla Thunderbird<150
150
Mozilla Thunderbird<140.10
140.10
Mozilla Firefox<140.10.0
Mozilla Firefox<150.0
Mozilla Thunderbird>=140.0<140.10.0

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 140.10
  2. Upgrade

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

    Fixed in 150
  3. Upgrade

    Upgrade Firefox to a version that resolves this vulnerability.

    Fixed in 150
  4. Upgrade

    Upgrade Firefox ESR to a version that resolves this vulnerability.

    Fixed in 140.10
  5. Upgrade

    Upgrade Thunderbird to a version that resolves this vulnerability.

    Fixed in 150
  6. Upgrade

    Upgrade Thunderbird ESR to a version that resolves this vulnerability.

    Fixed in 140.10

Event History

Apr 21, 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·12:40 PM
Data Sourced
via MITRE·12:40 PM
Description
Data Sourced
via NVD·01:16 PM
DescriptionSeverityWeaknessAffected Software
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
May 2, 58290
Event
via FIRST·04:05 AM

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-2026-6759?

CVE-2026-6759 is classified as a high severity vulnerability due to its potential to allow remote code execution.

2

How do I fix CVE-2026-6759?

To fix CVE-2026-6759, update to Firefox version 150, Firefox ESR version 140.10, Thunderbird version 150, or Thunderbird ESR version 140.10.

3

What does CVE-2026-6759 affect?

CVE-2026-6759 affects the Widget: Cocoa component in specific versions of Firefox and Thunderbird.

4

Is CVE-2026-6759 a zero-day vulnerability?

No, CVE-2026-6759 is not a zero-day as it has already been addressed by patches in the specified software versions.

5

How can I check if my software is vulnerable to CVE-2026-6759?

You can check your software version against the affected versions listed for CVE-2026-6759 to determine if you are vulnerable.

Company

Resources

Contact

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