dbcve.org
GlibcFramework / library · Gnu

CVE-2026-5450

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-20
Fix available
A fix is available. Upgrade to after 2.43 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Heap buffer overflow in GNU C Library's scanf implementation when using the %mc (malloc'd character match) format specifier with an explicit width greater than 1024. This corrupts one byte of heap memory and could enable arbitrary code execution.

MitigationUpgrade glibc to version 2.44 or later; alternatively, audit code to eliminate use of %mc with width specifiers >1024 and validate all scanf format strings.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
GlibcFramework / library
Affected:>= 2.7, <= 2.43

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed glibc version
    Run 'ldd --version' or '/lib/*/libc.so.6 --version' and note the version number shown
    Affected if The version shown is 2.7 through 2.43 (e.g., 2.31, 2.35, 2.43)
  2. Identify scanf-family function usage
    Search source code for calls to scanf, sscanf, fscanf, vscanf, vsscanf, or vfscanf using grep or string searching tools
    Affected if Any of these functions are used in the codebase
  3. Detect %mc format specifier usage
    Search format string arguments passed to scanf-family functions for the pattern '%[0-9]*mc' or '%mc'
    Affected if The pattern %mc or %Nmc (where N is any number) appears in scanf format strings
  4. Check for width specifier greater than 1024
    Examine any %mc format specifiers found and extract the numeric width value preceding 'mc'
    Affected if The width value before 'mc' is greater than 1024 (e.g., %1025mc, %2048mc)

You are affected if your glibc version is between 2.7 and 2.43 AND your code uses scanf-family functions with %mc format specifiers having a width greater than 1024

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.43
Interim mitigation

Upgrade glibc to version 2.44 or later; alternatively, audit code to eliminate use of %mc with width specifiers >1024 and validate all scanf format strings.

Recommended fix Moderate confidence

glibc 2.44 or later (upgrade to latest stable release available from your distribution or sourceware.org)

  1. 1. Identify all systems and applications that link against the affected glibc versions (2.7 through 2.43)
  2. 2. Check the current glibc version on target systems using: ldd --version or /lib64/libc.so.6
  3. 3. Plan for upgrade - glibc is a core system library; plan for appropriate maintenance windows and testing
  4. 4. For Linux distributions, apply security updates via the distribution's package manager (e.g., yum update glibc, apt-get update && apt-get install libc6, or dnf update glibc)
  5. 5. After updating, reboot systems as required to load the new glibc library
  6. 6. Verify the new glibc version is >= 2.44 using: ldd --version
  7. 7. Test all critical applications to ensure compatibility with the updated library
Caveat Minor risk - some legacy applications relying on specific glibc behavior may require recompilation; very old binaries linked against older glibc may need rebuilding

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Glibc Scoped from the published advisory
  • Consultation8.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,380
Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-5450 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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