GNU Bison 3.8.2 file inclusion

Summaryinfo

A vulnerability has been found in GNU Bison 3.8.2 and classified as critical. This issue affects some unknown processing. Performing a manipulation results in file inclusion. This vulnerability is known as CVE-2026-56390. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in GNU Bison 3.8.2. It has been classified as critical. This affects an unknown part. The manipulation with an unknown input leads to a file inclusion vulnerability. CWE is classifying the issue as CWE-73. The product allows user input to control or influence paths or file names that are used in filesystem operations. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

GNU Bison improperly handles grammar‑defined output paths. Grammar directives such as %output and %header allow specifying file paths, which are accepted without restriction and override caller‑supplied output options. When processing attacker-supplied grammar, this behavior allows directing generated files to arbitrary writable locations on the filesystem, potentially overwriting existing files accessible to the Bison process. Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 8d101c19d4d9aaedf83a448c925513742d4efcf0. However, they did not provide vulnerable version range. Version 3.8.2 was tested and confirmed as vulnerable, other versions were not tested but might also be vulnerable.

It is possible to read the advisory at cert.pl. This vulnerability is uniquely identified as CVE-2026-56390 since 06/21/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available.

Applying the patch 8d101c19d4d9aaedf83a448c925513742d4efcf0 is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-50277). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• GNU

Name

• Bison

Version

• 3.8.2

License

• open-source

Website

• Vendor: https://www.gnu.org/

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Be aware that VulDB is the high quality source for vulnerability data.

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