CVE-2026-56389: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-735p-4prj-f62v
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CVSS 8.6
CWE-78
Published
Advisory Summary

CVE-2026-56389 is a MODERATE (CVSS 8.6) security vulnerability vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-56389 at a Glance

CVE Identifier CVE-2026-56389
GHSA Identifier GHSA-735p-4prj-f62v
Severity MODERATE
CVSS v3.1 Base Score 8.6
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.6

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-56389

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-56389, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-56389 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-56389
cert.pl/en/posts/2026/07/cv... WEB
https://cert.pl/en/posts/2026/07/CVE-2026-56389
cgit.git.savannah.gnu.org/cgit/bison.git WEB
https://cgit.git.savannah.gnu.org/cgit/bison.git
cgit.git.savannah.gnu.org/cgit/bison.git/comm... WEB
https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=3169c1e7a2c6acc4c59dfcf8b089896d6881925b

Frequently Asked Questions

What is CVE-2026-56389?
CVE-2026-56389 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-56389?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-56389?
CVE-2026-56389 has a CVSS v3.1 base score of 8.6 (MODERATE) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
What CWE is associated with CVE-2026-56389?
CVE-2026-56389 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check Maven dependencies for CVE-2026-56389?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-735p-4prj-f62v",
  "modified" : "2026-08-24T18:31:26Z",
  "published" : "2026-07-29T12:31:23Z",
  "aliases" : [ "CVE-2026-56389" ],
  "details" : "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().\n \nWhen running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.\n\n\nMaintainers 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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-56389"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/en/posts/2026/07/CVE-2026-56389"
  }, {
    "type" : "WEB",
    "url" : "https://cgit.git.savannah.gnu.org/cgit/bison.git"
  }, {
    "type" : "WEB",
    "url" : "https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=3169c1e7a2c6acc4c59dfcf8b089896d6881925b"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-29T11:16:49Z"
  }
}