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.

Project Subscriptions

Vendors Products
Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8737-1 GNU C Library vulnerabilities
Ubuntu USN Ubuntu USN USN-8737-2 GNU C Library vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 14 Sep 2026 21:00:00 +0000

Type Values Removed Values Added
Description A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts. 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.
Title glibc: Buffer Overflow in strfmon right-justification padding Buffer overflow in strfmon and strfmon_l right-justification padding
Weaknesses CWE-122
References
Metrics cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

cvssV3_1

{'score': 7.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H'}


Mon, 31 Aug 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Gnu
Gnu glibc
Vendors & Products Gnu
Gnu glibc

Tue, 25 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
Description A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.
Title glibc: Buffer Overflow in strfmon right-justification padding
Weaknesses CWE-787
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H'}

threat_severity

Moderate


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: glibc

Published:

Updated: 2026-09-14T19:40:43.330Z

Reserved: 2026-08-10T18:42:03.154Z

Link: CVE-2026-19499

cve-icon Vulnrichment

Updated: 2026-09-14T19:40:39.869Z

cve-icon NVD

Status : Received

Published: 2026-09-14T18:17:45.753

Modified: 2026-09-14T20:16:43.250

Link: CVE-2026-19499

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-25T07:32:48Z

Links: CVE-2026-19499 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-15T13:45:07Z

Weaknesses