GNU C Library up to 2.43 malloc Character Match heap-based overflow

Summaryinfo

A vulnerability classified as critical has been found in GNU C Library up to 2.43. This affects an unknown part of the component malloc Character Match Handler. Performing a manipulation results in heap-based overflow. This vulnerability is identified as CVE-2026-5450. The attack is only possible with local access. There is not any exploit available.

Detailsinfo

A vulnerability classified as critical has been found in GNU C Library up to 2.43. This affects some unknown processing of the component malloc Character Match Handler. The manipulation with an unknown input leads to a heap-based overflow vulnerability. CWE is classifying the issue as CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

The weakness was released by Rocket Ma. It is possible to read the advisory at sourceware.org. This vulnerability is uniquely identified as CVE-2026-5450 since 04/02/2026. The exploitability is told to be easy. Attacking locally is a requirement. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 308167 (Linux Distros Unpatched Vulnerability : CVE-2026-5450), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (308167) and CERT Bund (WID-SEC-2026-1190). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Red Hat Enterprise Linux
• Fedora Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source GNU libc

Productinfo

Type

• Software Library

Vendor

• GNU

Name

• C Library

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.17
• 2.18
• 2.19
• 2.20
• 2.21
• 2.22
• 2.23
• 2.24
• 2.25
• 2.26
• 2.27
• 2.28
• 2.29
• 2.30
• 2.31
• 2.32
• 2.33
• 2.34
• 2.35
• 2.36
• 2.37
• 2.38
• 2.39
• 2.40
• 2.41
• 2.42
• 2.43

License

• open-source

Website

• Vendor: https://www.gnu.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

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Sourcesinfo

Entryinfo

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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