CVE-2026-16093: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-jmhg-9c54-p575
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CVSS 5.4
CWE-807
Published
Advisory Summary

CVE-2026-16093 is a MODERATE (CVSS 5.4) security vulnerability vulnerability (CWE-807: Reliance on Untrusted Inputs in a Security Decision) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-16093 at a Glance

CVE Identifier CVE-2026-16093
GHSA Identifier GHSA-jmhg-9c54-p575
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-807: Reliance on Untrusted Inputs in a Security Decision
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.4

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-16093

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-2026-16093, 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-807: Reliance on Untrusted Inputs in a Security Decision, where the product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism. 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

Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.

References

NVD — CVE-2026-16093 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-16093
access.redhat.com/errata/rhsa-2026:68... WEB
https://access.redhat.com/errata/RHSA-2026:68277
access.redhat.com/errata/rhsa-2026:68... WEB
https://access.redhat.com/errata/RHSA-2026:68278
Software Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-16093
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2501729

Frequently Asked Questions

What is CVE-2026-16093?
CVE-2026-16093 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-807: Reliance on Untrusted Inputs in a Security Decision.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-16093?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-16093?
CVE-2026-16093 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-16093?
CVE-2026-16093 is classified under CWE-807: Reliance on Untrusted Inputs in a Security Decision (The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.).
How can I check Maven dependencies for CVE-2026-16093?
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-jmhg-9c54-p575",
  "modified" : "2026-09-16T18:31:18Z",
  "published" : "2026-07-17T18:31:26Z",
  "aliases" : [ "CVE-2026-16093" ],
  "details" : "Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-16093"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:68277"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/errata/RHSA-2026:68278"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-16093"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2501729"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-807" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-07-17T17:17:14Z"
  }
}