CVE-2026-56389

Name	CVE-2026-56389
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1143158

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
bison (PTS)	bullseye	2:3.7.5+dfsg-1	vulnerable
	forky, sid, bookworm, trixie	2:3.8.2+dfsg-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
bison	source	(unstable)	(unfixed)			1143158

Notes

[trixie] - bison <no-dsa> (Minor issue)
[bookworm] - bison <postponed> (Minor issue)
[bullseye] - bison <postponed> (Minor issue)
https://cert.pl/en/posts/2026/07/CVE-2026-56389
https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=3169c1e7a2c6acc4c59dfcf8b089896d6881925b