GNU gawk up to 5.4.0 Directory Reader extension/readdir.c ftype buffer overflow

Summaryinfo

A vulnerability, which was classified as problematic, has been found in GNU gawk up to 5.4.0. The impacted element is the function ftype of the file extension/readdir.c of the component Directory Reader. Performing a manipulation results in buffer overflow. This vulnerability is cataloged as CVE-2026-40553. The attack must be initiated from a local position. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in GNU gawk up to 5.4.0. This affects the function ftype of the file extension/readdir.c of the component Directory Reader. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Buffer overflow vulnerability has been found in "extension/readdir.c" program file of gawk (ftype() routine). This issue could be used to crash the program and potentially to achieve code execution, although the latter has not been confirmed to be feasible. It affects gawk in versions 5.4.0 and below.

It is possible to read the advisory at cgit.git.savannah.gnu.org. This vulnerability is uniquely identified as CVE-2026-40553 since 04/14/2026. The exploitability is told to be easy. Attacking locally is a requirement. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/13/2026).

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

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Productinfo

Vendor

• GNU

Name

• gawk

Version

• 5.0
• 5.1
• 5.2
• 5.3
• 5.4.0

License

• open-source

Website

• Vendor: https://www.gnu.org/

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