Buffer overflow in strfmon and strfmon_l right-justification padding

Buffer overflow in strfmon and strfmon_l right-justification padding

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.

Source published

14 Sep 2026 17:11:12 UTC

Source modified

14 Sep 2026 19:40:43 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 7.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H