CVE-2026-19499: The GNU C Library Glibc

High severity, CVSS 7.7. EPSS: 0.3% chance of exploitation in the next 30 days.

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

Affected products

• The GNU C Library Glibc: from 2.38, up to and including 2.44

Published 2026-09-14. Last modified 2026-09-18.