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CVE-2026-56389— Arbitrary Command Execution in GNU Bison

Quick assessment

Affected
GNU Bison
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

GNU bison是美国GNU基金会开源的一种通用语法分析器生成工具。 GNU Bison 3.8.2版本存在命令注入漏洞，该漏洞源于对语法定义的配置变量处理不当，导致在运行bison --html时，攻击者提供的语法文件可覆盖XML到HTML转换的可执行文件，从而执行任意程序。

CVSS 6.8 · Medium EPSS 0.22% · P12

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 1

VendorProduct Version RangeStatus
GNU Bison 3.8.2 affected
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I. Basic Information for CVE-2026-56389

Vulnerability Information
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Vulnerability Title
Arbitrary Command Execution in GNU Bison
Source: CVE Program / CVE List V5
Vulnerability 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 Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:L/SI:L/SA:L
Source: CVE Program / CVE List V5
Vulnerability Type
OS命令中使用的特殊元素转义处理不恰当(OS命令注入)
Source: CVE Program / CVE List V5
Vulnerability Title
GNU Bison 命令注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
GNU bison是美国GNU基金会开源的一种通用语法分析器生成工具。 GNU Bison 3.8.2版本存在命令注入漏洞，该漏洞源于对语法定义的配置变量处理不当，导致在运行bison --html时，攻击者提供的语法文件可覆盖XML到HTML转换的可执行文件，从而执行任意程序。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
GNU Bison 3.8.2 -

II. Public POCs for CVE-2026-56389

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III. Intelligence Information for CVE-2026-56389

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Patches & Fixes for CVE-2026-56389 (1)

Security Blog Posts for CVE-2026-56389 (1)

IV. Related Vulnerabilities

Same product: Bison
Same vendor: GNU
Same weakness: CWE-78

V. Comments for CVE-2026-56389

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