Mozilla · Firefox Esr · CVE-2026-4696
**Name of the Vulnerable Software and Affected Versions**
Firefox versions prior to 149
Firefox ESR versions prior to 115.34
Firefox ESR versions prior to 140.9
Thunderbird versions prior to 149
Thunderbird versions prior to 140.9
**Description**
A use-after-free issue exists in the Layout: Text and Fonts component. This can potentially allow for unexpected behavior or compromise.
**Recommendations**
Update Firefox to version 149 or later.
Update Firefox ESR to version 115.34 or later.
Update Firefox ESR to version 140.9 or later.
Update Thunderbird to version 149 or later.
Update Thunderbird to version 140.9 or later.