CVE-2026-40551: Software Security Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-4r5q-f55r-9frx
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CWE-603
Published
Advisory Summary

CVE-2026-40551 is a HIGH security vulnerability vulnerability (CWE-603: Use of Client-Side Authentication) affecting Software libraries in the Maven ecosystem. The weakness occurs when a client/server product performs authentication within client code but not in server code, allowing server-side authentication to be bypassed via a modified client that omits the authentication check.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-40551 at a Glance

CVE Identifier CVE-2026-40551
GHSA Identifier GHSA-4r5q-f55r-9frx
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-603: Use of Client-Side Authentication
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2026-40551

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-2026-40551, 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-603: Use of Client-Side Authentication, where a client/server product performs authentication within client code but not in server code, allowing server-side authentication to be bypassed via a modified client that omits the authentication check. 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

mpGabinet performs client-side authentication. An attacker with access to any application instance connected to the backend server can bypass the login verification process by manipulating the application binary and authenticate as an arbitrary user. This issue affects mpGabinet version 23.12.19 and below.

References

NVD — CVE-2026-40551 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-40551
cert.pl/posts/2026/04/cve-2... WEB
https://cert.pl/posts/2026/04/CVE-2026-40550
www.binsoft.pl/produkty WEB
https://www.binsoft.pl/produkty
www.mpgabinet.pl WEB
https://www.mpgabinet.pl

Frequently Asked Questions

What is CVE-2026-40551?
CVE-2026-40551 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-603: Use of Client-Side Authentication.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-40551?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2026-40551?
CVE-2026-40551 is classified under CWE-603: Use of Client-Side Authentication (A client/server product performs authentication within client code but not in server code, allowing server-side authentication to be bypassed via a modified client that omits the authentication check.).
How can I check Maven dependencies for CVE-2026-40551?
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-4r5q-f55r-9frx",
  "modified" : "2026-09-30T12:35:09Z",
  "published" : "2026-04-28T15:30:50Z",
  "aliases" : [ "CVE-2026-40551" ],
  "details" : "mpGabinet performs client-side authentication. An attacker with access to any application instance connected to the backend server can bypass the login verification process by manipulating the application binary and authenticate as an arbitrary user.  \n\nThis issue affects mpGabinet version 23.12.19 and below.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:L/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-2026-40551"
  }, {
    "type" : "WEB",
    "url" : "https://cert.pl/posts/2026/04/CVE-2026-40550"
  }, {
    "type" : "WEB",
    "url" : "https://www.binsoft.pl/produkty"
  }, {
    "type" : "WEB",
    "url" : "https://www.mpgabinet.pl"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-603" ],
    "severity" : "HIGH",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-04-28T14:16:13Z"
  }
}