CVE-2026-5734 PUBLISHED

Memory safety bugs fixed in Firefox ESR 140.9.1, Thunderbird ESR 140.9.1, Firefox 149.0.2 and Thunderbird 149.0.2

Assigner: mozilla
Reserved: 07.04.2026 Published: 07.04.2026 Updated: 07.04.2026

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 affects Firefox < 149.0.2 and Firefox ESR < 140.9.1.

Product Status

Vendor Mozilla
Product Firefox
Versions
  • affected from unspecified to 149.0.2 (excl.)
Vendor Mozilla
Product Firefox ESR
Versions
  • affected from unspecified to 140.9.1 (excl.)

Credits

  • Brian Grinstead, Christian Holler, Tom Schuster and the Mozilla Fuzzing Team

References