CVE-2026-4721

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 149 Firefox ESR versions 115.33 through 140.8 Thunderbird versions prior to 149 Thunderbird ESR versions 140.8 through 140.9

Description The software contains memory safety bugs, some of which demonstrate evidence of memory corruption. It is presumed that, with sufficient effort, these bugs could potentially be exploited to execute arbitrary code.

Recommendations Update Firefox to version 149 or later. Update Firefox ESR to version 115.34 or later, or version 140.9 or later. Update Thunderbird to version 149 or later. Update Thunderbird ESR to version 140.9 or later.