CVE-2026-8974: Memory safety bugs fixed in Thunderbird 140.11 and Thunderbird 151

Published May 19, 2026
·
Updated

Memory safety bugs present in Firefox ESR 140.10 and Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.

Other sources

Memory safety bugs present in Thunderbird 140.10 and Thunderbird 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.

— Mozilla

Affected Software

8 affected componentsFixes available
Mozilla Firefox<151
151
Mozilla Firefox ESR<140.11
140.11
Mozilla Thunderbird<151
151
Mozilla Thunderbird<140.11
140.11
Mozilla Firefox<140.11.0
Mozilla Firefox<151.0.0
Mozilla Thunderbird<140.11
Mozilla Thunderbird<151.0.0

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 151
  2. Upgrade

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

    Fixed in 140.11
  3. Upgrade

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

    Fixed in 140.11
  4. Upgrade

    Upgrade Mozilla Firefox to a version that resolves this vulnerability.

    Fixed in 151
  5. Upgrade

    Upgrade Mozilla Thunderbird to a version that resolves this vulnerability.

    Fixed in 140.11
  6. Upgrade

    Upgrade Mozilla Thunderbird to a version that resolves this vulnerability.

    Fixed in 151

Event History

May 19, 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
Updated
via Mozilla·12:00 AM
DescriptionAffected Software
CVE Published
via MITRE·12:30 PM
Data Sourced
via MITRE·12:30 PM
Description
Data Sourced
via Red Hat·02:02 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·02:16 PM
DescriptionSeverityWeaknessAffected Software
Jun 29, 58424
Event
via FIRST·06:11 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-2026-8974?

CVE-2026-8974 has a high severity due to potential memory corruption that could lead to arbitrary code execution.

2

How do I fix CVE-2026-8974?

To fix CVE-2026-8974, update to Thunderbird 140.11, Thunderbird 151, Firefox ESR 140.11, or Firefox 151.

3

Which versions are affected by CVE-2026-8974?

CVE-2026-8974 affects Firefox ESR versions up to 140.10 and Firefox versions up to 150.

4

What are memory safety bugs related to CVE-2026-8974?

The memory safety bugs in CVE-2026-8974 are vulnerabilities that can potentially result in memory corruption.

5

Is CVE-2026-8974 exploitable?

Yes, with sufficient effort, the memory safety bugs identified in CVE-2026-8974 could be exploited to run arbitrary code.

Company

Resources

Contact

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