SEPTEMBER 14, 2026
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Case File

CVE-2026-56389

HIGH · CVSS 8.6 EPSS 0.16%

Source: NVD + CISA KEV + EPSS · Published 2026-07-29 · Last synced 2026-08-28

CyberRota Analysis

AI-Generated

GNU Bison is vulnerable during HTML report generation due to improper handling of grammar-defined configuration variables, allowing an attacker to execute arbitrary programs with the privileges of the Bison process. This vulnerability arises when an attacker provides a malicious grammar file that overrides the executable used for XML-to-HTML transformation. Users and maintainers of Bison, particularly those utilizing versions around 3.8.2, should prioritize addressing this issue to mitigate potential exploitation risks.

CVE
CVE-2026-56389
Severity
HIGH
CVSS
8.6
EPSS
0.16%

Original NVD 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.

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