Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

1. Apr 7, 2026 · NIST NVD

   Detected

   Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

2. Jul 15, 2026 · NIST NVD

   Updated

   Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

Affected

• cpe mozilla/firefoxversion unspecified
• cpe mozilla/thunderbirdversion unspecified

Sources

• CVE.orgVulnerability recordCVE-2026-5734

  Official CVE identifier

  cve.org
• NIST NVDVulnerability recordCVE-2026-5734

  Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. 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. This

  nvd.nist.gov

References

• Reference · access.redhat.com
• Reference · access.redhat.com
• Reference · access.redhat.com
• Broken Link · bugzilla.mozilla.org
• Vendor Advisory · mozilla.org
• Vendor Advisory · mozilla.org
• Reference · mozilla.org
• Reference · mozilla.org