---
title: "CVE-2026-44203: OpenAM has pre-auth Reflected XSS in OAuth2 / OIDC response_mode=form_post via state parameter (FormPostResponse.ftl)"
url: https://erroneo.us/security/cve/CVE-2026-44203/
description: "CVE-2026-44203 (org.openidentityplatform.openam:openam-oauth2 (Maven)): Open Access Management (OpenAM) is an access management solution. Prior to 16.1.1…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-09-15
date_modified: 2026-09-17
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-44203"
kev: false
cvss: 8.3
epss: 0.00593
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-44203: OpenAM has pre-auth Reflected XSS in OAuth2 / OIDC response_mode=form_post via state parameter (FormPostResponse.ftl)

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.6% , percentile 48: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 48% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Only applies if your dependency tree includes org.openidentityplatform.openam:openam-oauth2 (Maven) >= 13.0.0, < 16.1.1, fixed in 16.1.1 . Check your lockfile, including transitive dependencies.

## What it is

Open Access Management (OpenAM) is an access management solution. Prior to 16.1.1, the OAuth 2.0 and OpenID Connect authorization endpoint does not sufficiently encode user-supplied parameters before FormPostResponse.ftl and checkSession.ftl render them into HTML for the formpost response mode. An unauthenticated attacker can induce a user to open a crafted authorization request and execute script in the OpenAM origin. This issue is fixed in version 16.1.1.

## Affected packages

- Maven `org.openidentityplatform.openam:openam-oauth2` >= 13.0.0, < 16.1.1 → fixed: 16.1.1

## Affected products (CVE record)

- OpenIdentityPlatform OpenAM: < 16.1.1

## Severity

- GitHub_M CVSS 4.0: 8.3 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:H/VA:N/SC:L/SI:H/SA:N`
- GitHub CVSS 3.1: 9.3 `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.59% probability of exploitation activity in the next 30 days; percentile 48.

## Sources

- [GitHub Advisory GHSA-fq9h-c788-fx73](https://github.com/advisories/GHSA-fq9h-c788-fx73)
- [CVE.org record CVE-2026-44203](https://www.cve.org/CVERecord?id=CVE-2026-44203)
- [NVD entry CVE-2026-44203](https://nvd.nist.gov/vuln/detail/CVE-2026-44203)
- [github.com](https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-fq9h-c788-fx73)
- [github.com](https://github.com/OpenIdentityPlatform/OpenAM/commit/078bd4754905f5130eaa7bbe45f958eaeb7fd0d7)
- [github.com](https://github.com/OpenIdentityPlatform/OpenAM/releases/tag/16.1.1)

---
Source page: https://erroneo.us/security/cve/CVE-2026-44203/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt