CVE-2026-44203: Openam oauth2 Cross-Site Scripting Vulnerability

CRITICAL
Advisory Identifier: GHSA-fq9h-c788-fx73
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CVSS 9.3
CWE-79
Published
Advisory Summary

CVE-2026-44203 is a CRITICAL (CVSS 9.3) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Openam oauth2 libraries in the Maven ecosystem. The issue involves openam has pre-auth reflected xss in oauth2 / oidc response_mode=form_post via state parameter (formpostresponse.ftl). Remediation is available by upgrading affected packages to version 16.1.1.

CVE-2026-44203 at a Glance

CVE Identifier CVE-2026-44203
GHSA Identifier GHSA-fq9h-c788-fx73
Severity CRITICAL
CVSS v3.1 Base Score 9.3
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Openam oauth2
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 9.3

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:R/S:C/C:H/I:H/A:N).

Attack Vector Network (AV:N)
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 None (A:N)

How to Fix CVE-2026-44203

To remediate this vulnerability, upgrade all affected Openam 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.openidentityplatform.openam:openam-oauth2 fixed: 16.1.1 
<dependency>
    <groupId>org.openidentityplatform.openam</groupId>
    <artifactId>openam-oauth2</artifactId>
    <version>16.1.1</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.openidentityplatform.openam

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-44203, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.openidentityplatform.openam

Analyze the terminal output to locate any version of Openam oauth2 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 16.1.1), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.openidentityplatform.openam 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Openam 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

### Summary The OAuth 2.0 / OpenID Connect authorization endpoint does not sufficiently sanitize certain user-supplied parameters before incorporating them into the HTML response generated for the `form_post` response mode. This may allow an attacker to inject content into the rendered page in the context of the OpenAM origin.

CVE-2026-44203 Affected Openam oauth2 Versions

1 component(s)
Fixed Versions:
16.1.1
Product / Package Ecosystem Affected Versions Fixed Version
org.openidentityplatform.openam:openam-oauth2
maven/org.openidentityplatform.openam/openam-oauth2
Maven
≥ 13.0.0
< 16.1.1
16.1.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-fq9h-c788-fx73
Openam oauth2 Source Repository REPOSITORY
https://github.com/OpenIdentityPlatform/OpenAM
Openam oauth2 Release RELEASE
https://github.com/OpenIdentityPlatform/OpenAM/releases/tag/16.1.1

Frequently Asked Questions

What is CVE-2026-44203?
CVE-2026-44203 is a security vulnerability in Openam oauth2 involving OpenAM has pre-auth Reflected XSS in OAuth2 / OIDC response_mode=form_post via state parameter (FormPostResponse.ftl) under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Openam oauth2 versions are affected?
Affected versions include releases prior to 16.1.1 across affected packages: org.openidentityplatform.openam:openam-oauth2.
What version fixes CVE-2026-44203?
Upgrading to 16.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is openam-oauth2 affected?
Yes, org.openidentityplatform.openam:openam-oauth2 is affected in releases prior to 16.1.1. Upgrade your dependency to 16.1.1 or later.
What is the CVSS score of CVE-2026-44203?
CVE-2026-44203 has a CVSS v3.1 base score of 9.3 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.
What CWE is associated with CVE-2026-44203?
CVE-2026-44203 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check Maven dependencies for CVE-2026-44203?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.openidentityplatform.openam'. 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-fq9h-c788-fx73",
  "modified" : "2026-06-22T20:11:49Z",
  "published" : "2026-06-22T20:11:49Z",
  "aliases" : [ "CVE-2026-44203" ],
  "summary" : "OpenAM has pre-auth Reflected XSS in OAuth2 / OIDC response_mode=form_post via state parameter (FormPostResponse.ftl)",
  "details" : "### Summary\n\nThe OAuth 2.0 / OpenID Connect authorization endpoint does not sufficiently sanitize certain user-supplied parameters before incorporating them into the HTML response generated for the `form_post` response mode. This may allow an attacker to inject content into the rendered page in the context of the OpenAM origin.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.openidentityplatform.openam:openam-oauth2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "13.0.0"
      }, {
        "fixed" : "16.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-fq9h-c788-fx73"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/OpenIdentityPlatform/OpenAM"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/OpenIdentityPlatform/OpenAM/releases/tag/16.1.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-22T20:11:49Z",
    "nvd_published_at" : null
  }
}