CVE-2026-56390
MEDIUM
MEDIUM
Priority: 0.01
BB Relevance:
34/100
Published: 2026-07-29
Modified: 2026-10-23
First seen: 2026-10-29
Status: active
Attack Surface
Low Complexity
No Auth
CVSS Vector Breakdown
AV:
Local
AC:
Low
PR:
None
UI:
Active
S:
X
AT:
None
VC:
None
VI:
Low
VA:
None
Description
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.
Weakness Classification (1)
References & Advisories (3)
Third Party Advisory
Product
Patch