CVE-2026-56390
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.
- Score
- 4.6 medium
- Published
- 2026-07-29
- Links
- NVD · cve.org · Report wrong data
Matched ports (1)
| Port | Package | Version | Status | Maintainer |
|---|---|---|---|---|
| devel/bison | bison | 3.8.2_2,1 | unaddressed | sunpoet@FreeBSD.org |
Template for a VuXML entry
Range taken from the CVE record, check it before committing. make newentry in security/vuxml creates the vid.
<vuln vid="FIXME (make newentry)">
<topic>FIXME -- FIXME</topic>
<affects>
<package>
<name>bison</name>
<range><lt>FIXME</lt></range>
</package>
</affects>
<description>
<body xmlns="http://www.w3.org/1999/xhtml">
<p>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.</p>
</body>
</description>
<references>
<cvename>CVE-2026-56390</cvename>
<url>https://nvd.nist.gov/vuln/detail/CVE-2026-56390</url>
</references>
<dates>
<discovery>2026-07-29</discovery>
<entry>2026-10-26</entry>
</dates>
</vuln>