Description
GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp().
When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.
Maintainers of this project were notified about this vulnerability, and fixed the issue in commit 3169c1e7a2c6acc4c59dfcf8b089896d6881925b. 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 26.04 LTS | bison | 2:3.8.2+dfsg-1ubuntu0.26.04.1 | USN-8777-1 |
| Ubuntu 24.04 LTS | bison | 2:3.8.2+dfsg-1ubuntu0.24.04.1 | USN-8777-1 |
| Ubuntu 22.04 LTS | bison | 2:3.8.2+dfsg-1ubuntu0.22.04.1 | USN-8777-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | bison | 3.8.2-2 | — |
Advisories 1
- USN-8777-1 bison vulnerability Ubuntu Security Notices (USN) · Sep 18, 2026