Bug 2516215 - CVE-2026-56389 bison: GNU Bison: Arbitrary Code Execution via malicious grammar file [fedora-all]
Summary: CVE-2026-56389 bison: GNU Bison: Arbitrary Code Execution via malicious gramm...
Keywords:
Status: NEW
Alias: None
Product: Fedora
Classification: Fedora
Component: bison
Version: rawhide
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: ---
Assignee: Arjun Shankar
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard: {"flaws": ["48f4f255-7c9a-497c-abc8-6...
Depends On:
Blocks: CVE-2026-56389
TreeView+ depends on / blocked
 
Reported: 2026-08-14 22:39 UTC by Siddharth Sharma
Modified: 2026-08-21 13:48 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Type: ---
Embargoed:


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System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker FC-4764 0 None None None 2026-08-21 13:48:38 UTC

Description Siddharth Sharma 2026-08-14 22:39:22 UTC
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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.


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