Medium [CVE-2026-56389] Arbitrary Code Execution via malicious grammar file
This medium-severity Red Hat Linux advisory covers CVE-2026-56389 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
Arbitrary Code Execution via malicious grammar file. Red Hat rates this moderate (CVSS 5.5).
Weakness: CWE-78.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; and 3 more.
Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4; Red Hat package: bison.
- 3.8.2
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- To mitigate this vulnerability, avoid processing untrusted or unverified grammar files with the `bison --html` command. Restrict the use of `bison --html` to trusted input sources only. This operational control reduces the risk of arbitrary code execution by preventing the vulnerable code path from being triggered with malicious input.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
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