CVE-2026-50623: Cxf rt rs security oauth2 Authentication Bypass Vulnerability

MODERATE
Advisory Identifier: GHSA-542g-m3fx-q86f
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CVSS 6.5
CWE-287
Published
Advisory Summary

CVE-2026-50623 is a MODERATE (CVSS 6.5) authentication bypass vulnerability (CWE-287: Improper Authentication) affecting Cxf rt rs security oauth2 libraries in the Maven ecosystem. The issue involves apache cxf has authentication bypass in oauth2 tokenintrospectionservice. Remediation is available by upgrading affected packages to version 4.2.2, 4.1.7.

CVE-2026-50623 at a Glance

CVE Identifier CVE-2026-50623
GHSA Identifier GHSA-542g-m3fx-q86f
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-287: Improper Authentication
Affected Product Cxf rt rs security oauth2
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

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

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
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-2026-50623

To remediate this vulnerability, upgrade all affected Cxf rt rs security oauth2 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.apache.cxf:cxf-rt-rs-security-oauth2 fixed: 4.2.2 
<dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-rs-security-oauth2</artifactId>
    <version>4.2.2</version>
</dependency>
org.apache.cxf:cxf-rt-rs-security-oauth2 fixed: 4.1.7 
<dependency>
    <groupId>org.apache.cxf</groupId>
    <artifactId>cxf-rt-rs-security-oauth2</artifactId>
    <version>4.1.7</version>
</dependency>
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 -Dincludes=org.apache.cxf

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-50623, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.apache.cxf

Analyze the terminal output to locate any version of Cxf rt rs security oauth2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.2.2), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.apache.cxf 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-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. In Cxf rt rs security oauth2, 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

An authentication bypass vulnerability exists in the OAuth2 TokenIntrospectionService in Apache CXF. Due to a missing 'throw' keyword in the security context check, the introspection endpoint (/services/oauth2/introspect) can be accessed by any unauthenticated network attacker. However note that this is a safeguard only in the case that someone forgot to enable authentication on the service. Users are recommended to upgrade to version 4.2.2 or 4.1.7, which fixes this issue.

CVE-2026-50623 Affected Cxf rt rs security oauth2 Versions

2 component(s)
Fixed Versions:
4.2.24.1.7
Product / Package Ecosystem Affected Versions Fixed Version
org.apache.cxf:cxf-rt-rs-security-oauth2
maven/org.apache.cxf/cxf-rt-rs-security-oauth2
Maven
≥ 4.2.0
< 4.2.2
4.2.2
org.apache.cxf:cxf-rt-rs-security-oauth2
maven/org.apache.cxf/cxf-rt-rs-security-oauth2
Maven
< 4.1.7
4.1.7

References

NVD — CVE-2026-50623 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-50623
Cxf rt rs security oauth2 Source Repository REPOSITORY
https://github.com/apache/cxf
lists.apache.org/thread/ydzj8m5mqmjy... WEB
https://lists.apache.org/thread/ydzj8m5mqmjy13xgyj9mkk9hfff63qq7
Cxf rt rs security oauth2 Security Information SECURITY
http://www.openwall.com/lists/oss-security/2026/06/11/3

Frequently Asked Questions

What is CVE-2026-50623?
CVE-2026-50623 is a security vulnerability in Cxf rt rs security oauth2 involving Apache CXF has Authentication Bypass in OAuth2 TokenIntrospectionService under CWE-287: Improper Authentication.
Which Cxf rt rs security oauth2 versions are affected?
Affected versions include releases prior to 4.2.2, 4.1.7 across affected packages: org.apache.cxf:cxf-rt-rs-security-oauth2.
What version fixes CVE-2026-50623?
Upgrading to 4.2.2, 4.1.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is cxf-rt-rs-security-oauth2 affected?
Yes, org.apache.cxf:cxf-rt-rs-security-oauth2 is affected in releases prior to 4.2.2, 4.1.7. Upgrade your dependency to 4.2.2, 4.1.7 or later.
What is the CVSS score of CVE-2026-50623?
CVE-2026-50623 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2026-50623?
CVE-2026-50623 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check Maven dependencies for CVE-2026-50623?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.apache.cxf'. 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-542g-m3fx-q86f",
  "modified" : "2026-08-20T18:31:09Z",
  "published" : "2026-06-12T12:31:33Z",
  "aliases" : [ "CVE-2026-50623" ],
  "summary" : "Apache CXF has Authentication Bypass in OAuth2 TokenIntrospectionService",
  "details" : "An authentication bypass vulnerability exists in the OAuth2 TokenIntrospectionService in Apache CXF. Due to a missing 'throw' keyword in the security context check, the introspection endpoint (/services/oauth2/introspect) can be accessed by any unauthenticated network attacker. However note that this is a safeguard only in the case that someone forgot to enable authentication on the service. Users are recommended to upgrade to version 4.2.2 or 4.1.7, which fixes this issue.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.cxf:cxf-rt-rs-security-oauth2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0"
      }, {
        "fixed" : "4.2.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.apache.cxf:cxf-rt-rs-security-oauth2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-50623"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apache/cxf"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread/ydzj8m5mqmjy13xgyj9mkk9hfff63qq7"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2026/06/11/3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-20T18:31:09Z",
    "nvd_published_at" : "2026-06-12T10:16:22Z"
  }
}