---
id: CVE-2026-5450
title: scanf %mc off-by-one heap buffer overflow
summary: >-
  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 ov…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: adp
cwe:
  - CWE-122
vendor: The GNU C Library
product: glibc
affected:
  - glibc >= 2.7 < *
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-04-21T16:11:50.875542Z'
exploitAvailable: true
published: '2026-04-20'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:12:13.391Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-5450'
references:
  - url: 'https://sourceware.org/bugzilla/show_bug.cgi?id=CVE-2026-5450'
  - url: >-
      https://inbox.sourceware.org/libc-announce/b11f0003-6ec1-4bd6-b9de-9e38a4efeca3@redhat.com/T/#u
tags:
  - cve.org
  - exploit-available
epss: 0.00718
epssPercentile: 0.5281
ingestedAt: '2026-10-15T05:52:46.047Z'
---

## Overview

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.

## Affected

- `glibc >= 2.7 < *`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.