CVE-2026-56390

bison: GNU Bison: Arbitrary file overwrite via grammar-defined output paths

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Severity

Moderate

Red Hat Product Security

5.6

CVSS 3.1

Review impact separately from score.

Published · July 29, 2026

Updated · September 1, 2026

Description

A flaw was found in GNU Bison. When processing attacker-supplied grammar, the software improperly handles grammar-defined output paths. This allows an attacker to use directives such as %output and %header to specify arbitrary file paths. Consequently, generated files can be directed to any writable location on the filesystem, potentially overwriting existing files and leading to data integrity issues.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 5.6
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:L

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')