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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| GNU | Bison | 3.8.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | bison | No fix yet | — |
| Debian 13 | bison | No fix yet | — |
| Debian 12 | bison | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | bison | No fix yet | — |
| Ubuntu 26.04 LTS | bison | No fix yet | — |
| Ubuntu 24.04 LTS | bison | No fix yet | — |
| Ubuntu 22.04 LTS | bison | No fix yet | — |
| Ubuntu 20.04 LTS | bison | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | bison | No fix yet | — |
| Ubuntu 16.04 LTS | bison | No fix yet | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | bison | 3.8.2-2 | — |