GNU coreutils up to 9.11 Multibyte Input find_field out-of-bounds

Summaryinfo

A vulnerability was found in GNU coreutils up to 9.11. It has been declared as problematic. Affected by this issue is the function find_field of the component Multibyte Input Handler. The manipulation results in out-of-bounds. This vulnerability was named CVE-2026-56391. The attack needs to be approached locally. There is no available exploit.

Detailsinfo

A vulnerability classified as problematic has been found in GNU coreutils up to 9.11. Affected is the function find_field of the component Multibyte Input Handler. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

GNU coreutils uniq is vulnerable to an out‑of‑bounds read due to incorrect handling of multibyte input when the -w (--check-chars) option is used. The find_field() function miscalculates the byte length of characters by repeatedly processing a fixed pointer instead of advancing through the input, resulting in an inflated length value. This incorrect length is later used in a memcmp operation, causing reads beyond the allocated buffer when processing crafted multibyte input. When running GNU coreutils uniq with attacker-provided arguments, this behavior leads to a crash and potential adjacent heap memory exposure. This issue has been fixed in the commit d64e35a8a4c0e4608321433e0d84d917e4e36371.

The advisory is available at cert.pl. This vulnerability is traded as CVE-2026-56391 since 06/21/2026. The exploitability is told to be easy. Local access is required to approach this attack. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Applying the patch d64e35a8a4c0e4608321433e0d84d917e4e36371 is able to eliminate this problem.

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Productinfo

Vendor

• GNU

Name

• coreutils

Version

• 9.0
• 9.1
• 9.2
• 9.3
• 9.4
• 9.5
• 9.6
• 9.7
• 9.8
• 9.9
• 9.10
• 9.11

License

• open-source

Website

• Vendor: https://www.gnu.org/

CPE 2.3info

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CPE 2.2info

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