Buffer overflow in The GNU C Library Glibc

CVE-2026-19499

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H.

EPSS exploit prediction

EPSS: 0.003 (22.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 22.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-19499: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-19499?
CVE-2026-19499 is a high-severity vulnerability in The GNU C Library Glibc, classified under Heap-based Buffer Overflow. CVSS score: 7.7/10. Published 2026-09-14.
How severe is CVE-2026-19499?
High severity. CVSS v3 base score is 7.7 out of 10.