Critical 9.8Published Apr 20, 2026

CVE-2026-5450scanf %mc off-by-one heap buffer overflow

Updated under an hour ago (2026-10-19 06:30 UTC)

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It affects The GNU C Library glibc and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for The GNU C Library glibc

Exploited in the last 30 days

Calling the scanf family of functions with a %mc (malloc'd character match) in the GNU C Library version 2.7 to version 2.43 with a format width specifier with an explicit width greater than 1024 could result in a one byte heap buffer overflow.

CVSS: 9.8 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-122
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: glibc
NVD analysis: Modified
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

The GNU C Library glibc gnu_c_library:glibc (from the name)	from 2.7	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.5 before V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.5 before V3.1.6	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.5 before V3.1.6	CISA ADP
gnu glibc gnu:glibc	from 2.7 through 2.43	NVD

References

https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450issue-tracking, exploit
https://inbox.sourceware.org/libc-announce/b11f0003-6ec1-4bd6-b9de-9e38a4efeca3@redhat.com/T/#umailing-list, third-party-advisory
https://cert-portal.siemens.com/productcert/html/ssa-082556.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.