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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

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 · score source

EPSS

• CVE-2026-44203: 0.59% estimated exploitation activity in the next 30 days; percentile 48.42 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

22 Jun 2026, 20:11 UTC

Last modified by the source

28 Oct 2026, 15:45 UTC

Source last checked

29 Oct 2026, 06:45 UTC

1. Revision 3 · amended · 29 Oct 2026

   Amended from osv record GHSA-fq9h-c788-fx73

2. Revision 2 · amended · 28 Oct 2026

   Amended from ghsa record GHSA-fq9h-c788-fx73

3. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fq9h-c788-fx73

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# Patch Next advisory brief: CVE-2026-44203

Advisory: OpenAM has pre-auth Reflected XSS in OAuth2 / OIDC response_mode=form_post via state parameter (FormPostResponse.ftl)
IDs: CVE-2026-44203, GHSA-fq9h-c788-fx73
Record: https://patchnext.com/advisories/cve-2026-44203 (revision 3, source checked 29 Oct 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.openidentityplatform.openam:openam-oauth2 16.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.openidentityplatform.openam:openam-oauth2: affected >= 13.0.0, < 16.1.1; fixed in 16.1.1

## Suggested inspection (read-only)
- Maven org.openidentityplatform.openam:openam-oauth2: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.openidentityplatform.openam:openam-oauth2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-fq9h-c788-fx73 (GitHub-reviewed advisory GHSA-fq9h-c788-fx73 lists affected ranges: Maven org.openidentityplatform.openam:openam-oauth2 >=13.0.0 <16.1.1)
- Verified: https://osv.dev/vulnerability/GHSA-fq9h-c788-fx73 (OSV record GHSA-fq9h-c788-fx73 lists affected ranges: Maven org.openidentityplatform.openam:openam-oauth2 >=13.0.0 <16.1.1 (fixed))

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