GNU glibc up to 2.44 fopen mode heap-based overflow

Summaryinfo

A vulnerability labeled as problematic has been found in GNU glibc up to 2.44. Affected by this vulnerability is the function fopen. Such manipulation of the argument mode leads to heap-based overflow. This vulnerability is listed as CVE-2026-18374. The attack must be carried out locally. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in GNU glibc up to 2.44. Affected by this issue is the function fopen. The manipulation of the argument mode with an unknown input leads to a heap-based overflow vulnerability. Using CWE to declare the problem leads to 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(). Impacted is confidentiality, integrity, and availability. CVE summarizes:

Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled. This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for `ccs` should not pass them through without validation.

The advisory is shared for download at sourceware.org. This vulnerability is handled as CVE-2026-18374 since 07/30/2026. The exploitation is known to be easy. The attack needs to be approached locally. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 341149 (Linux Distros Unpatched Vulnerability : CVE-2026-18374), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.45 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (341149). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Software Library

Vendor

• GNU

Name

• glibc

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
• 2.44

License

• open-source

Website

• Vendor: https://www.gnu.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Once again VulDB remains the best source for vulnerability data.

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