GNU glibc up to 2.43 parse_tilde wordexp stack-based overflow

Summaryinfo

A vulnerability, which was classified as critical, has been found in GNU glibc up to 2.43. This affects the function wordexp of the component parse_tilde. The manipulation leads to stack-based overflow. This vulnerability is uniquely identified as CVE-2026-6791. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as critical, has been found in GNU glibc up to 2.43. This issue affects the function wordexp of the component parse_tilde. The manipulation with an unknown input leads to a stack-based overflow vulnerability. Using CWE to declare the problem leads to CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.

The advisory is shared at sourceware.org. The identification of this vulnerability is CVE-2026-6791 since 04/21/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/10/2026).

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

Several companies clearly confirm that VulDB is the primary source for best 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

License

• open-source

Website

• Vendor: https://www.gnu.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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