CVE-2026-6766: Incorrect boundary conditions in the Libraries component in NSS

Published Apr 21, 2026
·
Updated

Incorrect boundary conditions in the Libraries component in NSS. 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<140.10.0

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 Mozilla Firefox to a version that resolves this vulnerability.

    Fixed in 150
  4. Upgrade

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

    Fixed in 140.10
  5. Upgrade

    Upgrade Mozilla Thunderbird to a version that resolves this vulnerability.

    Fixed in 150
  6. Upgrade

    Upgrade Mozilla 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

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-2026-6766?

CVE-2026-6766 is classified with moderate severity due to incorrect boundary conditions.

2

How do I fix CVE-2026-6766?

To fix CVE-2026-6766, update to Firefox versions 150, Firefox ESR 140.10, Thunderbird 150, or Thunderbird ESR 140.10.

3

Which products are affected by CVE-2026-6766?

CVE-2026-6766 affects Mozilla Firefox, Firefox ESR, and Thunderbird versions prior to the specified fixed versions.

4

What are the potential impacts of CVE-2026-6766?

The impact of CVE-2026-6766 may include application crashes or unexpected behavior due to incorrect handling of boundary conditions.

5

What should I do if I can't update my software for CVE-2026-6766?

If you cannot update your software for CVE-2026-6766, consider implementing additional security measures or using an alternative solution.

Company

Resources

Contact

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