CVE-2026-109723

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 158 Firefox ESR versions prior to 153.5 Thunderbird versions prior to 158 Thunderbird versions prior to 153.5

Description An integer overflow exists within the Layout: Text and Fonts component. An integer overflow occurs when an arithmetic operation attempts to create a numeric value that is too large to be stored in the allotted memory space.

Recommendations Update Firefox to version 158. Update Firefox ESR to version 153.5. Update Thunderbird to version 158. Update Thunderbird to version 153.5.