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

Advisory record · `GHSA-fq9h-c788-fx73`

- **Identifiers:** `GHSA-fq9h-c788-fx73` · `CVE-2026-44203`
- **State:** Confirmed
- **Severity:** CVSS 8.3 High
- **Critical:** No
- **Weakness (CWE):** [CWE-79](https://cwe.mitre.org/data/definitions/79.html)
- **Tags:** [Cross-site scripting (XSS)](https://agentprime.io/advisories/tag/xss.md)
- **Published:** 22 Jun 2026
- **Updated:** 28 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 Jun 2026, 20:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `org.openidentityplatform.openam:openam-oauth2` (Maven): affected `>=13.0.0, <16.1.1`; fixed in `16.1.1`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> OpenAM's openam-oauth2 Maven package, versions 13.0.0 up to 16.1.1 (exclusive), is affected by a reflected cross-site scripting flaw in the OAuth 2.0 and OpenID Connect authorization endpoint when the form_post response mode is used. The source gives few details beyond the fact that user-supplied parameters are not sufficiently sanitized before being placed in the generated HTML page. An unauthenticated attacker could potentially inject content into the page under the OpenAM origin by getting a user to open a crafted link. Upgrade to openam-oauth2 version 16.1.1.

Written 2 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 8.3 High, CVSS 4.0: `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`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0059, the 48th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:16 UTC: First seen by agentprime
- 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-fq9h-c788-fx73)

## Sources

- [GitHub Advisory Database: GHSA-fq9h-c788-fx73](https://github.com/advisories/GHSA-fq9h-c788-fx73)
- [OSV: GHSA-fq9h-c788-fx73](https://osv.dev/vulnerability/GHSA-fq9h-c788-fx73)
- <https://github.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-fq9h-c788-fx73>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-44203>
- <https://github.com/OpenIdentityPlatform/OpenAM/commit/078bd4754905f5130eaa7bbe45f958eaeb7fd0d7>
- <https://github.com/OpenIdentityPlatform/OpenAM>
- <https://github.com/OpenIdentityPlatform/OpenAM/releases/tag/16.1.1>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-fq9h-c788-fx73>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-fq9h-c788-fx73/>. Everything for agents: <https://agentprime.io/llms.txt>.