CVE-2026-40856: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-xw9f-4565-4fvc
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CWE-306
Published
Advisory Summary

CVE-2026-40856 is a HIGH security vulnerability vulnerability (CWE-306: Missing Authentication for Critical Function) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-40856 at a Glance

CVE Identifier CVE-2026-40856
GHSA Identifier GHSA-xw9f-4565-4fvc
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-306: Missing Authentication for Critical Function
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-40856

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-2026-40856, 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-306: Missing Authentication for Critical Function, where the product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. 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

WNC T-Mobile 5G Box IDU router is vulnerable to improper access control. The vulnerability exists in the wnc_maccheck.cgi endpoint, which is accessible without authentication. It allows a remote attacker to retrieve sensitive configuration data, including the administrator web password, WiFi passphrase, and technical device information.This issue has been fixed in firmware version 1.1.0.651412

References

NVD — CVE-2026-40856 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40856
cert.pl/posts/2026/09/cve-2... WEB
https://cert.pl/posts/2026/09/CVE-2026-40854

Frequently Asked Questions

What is CVE-2026-40856?
CVE-2026-40856 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-306: Missing Authentication for Critical Function.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-40856?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-40856?
CVE-2026-40856 is classified under CWE-306: Missing Authentication for Critical Function (The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources.).
How can I check Maven dependencies for CVE-2026-40856?
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-xw9f-4565-4fvc",
  "modified" : "2026-09-16T12:30:46Z",
  "published" : "2026-09-16T12:30:46Z",
  "aliases" : [ "CVE-2026-40856" ],
  "details" : "WNC T-Mobile 5G Box IDU router is vulnerable to improper access control. The vulnerability exists in the wnc_maccheck.cgi endpoint, which is accessible without authentication. It allows a remote attacker to retrieve sensitive configuration data, including the administrator web password, WiFi passphrase, and technical device information.This issue has been fixed in firmware version 1.1.0.651412",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/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-2026-40856"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/posts/2026/09/CVE-2026-40854"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-306" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-09-16T12:17:03Z"
  }
}