CVE-2026-56389

Arbitrary program execution via tool.xsltproc override

Published Jul 29, 2026 · Updated Jul 29, 2026

Command injection in GNU Bison 3.8.2 allows local users to execute arbitrary programs through a grammar processed with the --html option. The HTML-report path accepts a grammar-defined tool.xsltproc value without restriction and passes it directly to execvp(). Exploitation requires processing an attacker-provided grammar with --html, and the selected program runs with the Bison process's privileges.

CVSS severity6.8
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in GNU Bison 3.8.2 allows local users to execute arbitrary programs through a grammar processed with the --html option. The HTML-report path accepts a grammar-defined tool.xsltproc value without restriction and passes it directly to execvp(). Exploitation requires processing an attacker-provided grammar with --html, and the selected program runs with the Bison process's privileges.

The record

CVE
CVE-2026-56389
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
The GnuPG Project
Product
GNU Bison
Classifications
CWE-78, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=3.8.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The GnuPG Project · GNU Bisonversion=3.8.2

Published CVSS scores

6.8CERT PolskaCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:L/SC:L/SI:L/SA:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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