# SimpleSAMLphp SP accepts a response from an unexpected IdP when unsigned \`Response/InResponseTo\` is combined with a signed assertion lacking \`SubjectConfirmationData/InResponseTo\`

Advisory record · `GHSA-q8r6-xj3f-wrrm`

- **Identifiers:** `GHSA-q8r6-xj3f-wrrm` · `CVE-2026-49284` · `PKSA-569h-6vqh-5xr3`
- **State:** Confirmed
- **Severity:** CVSS 7.1 High
- **Critical:** No
- **Weakness (CWE):** [CWE-345](https://cwe.mitre.org/data/definitions/345.html)
- **Tags:** [CWE-345](https://agentprime.io/advisories/tag/cwe-345.md)
- **Published:** 2 Jul 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 2 Jul 2026, 20:47 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `simplesamlphp/simplesamlphp` (Packagist): affected `>=2.5.0, <2.5.2 || <2.4.7`; fixed in `2.5.2`, `2.4.7`

## Machine-written summary

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

> SimpleSAMLphp versions below 2.4.7 and from 2.5.0 up to (not including) 2.5.2 are affected. When a saved SP login state expects one identity provider but the assertion consumer service accepts a valid response from a different trusted IdP, the SP only logs a warning and continues, and an unsigned InResponseTo attribute can be accepted for that response. An attacker who controls or can obtain a signed assertion from a lower-trust trusted IdP could therefore bypass a flow meant to route users to a specific IdP, which matters most in multi-IdP deployments. Upgrade to 2.4.7 or 2.5.2.

Written 31 Oct 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

- 7.1 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0022, the 12th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:00 UTC: First seen by agentprime
- 31 Oct 2026, 14:00 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-q8r6-xj3f-wrrm)

## Sources

- [GitHub Advisory Database: GHSA-q8r6-xj3f-wrrm](https://github.com/advisories/GHSA-q8r6-xj3f-wrrm)
- [OSV: GHSA-q8r6-xj3f-wrrm](https://osv.dev/vulnerability/GHSA-q8r6-xj3f-wrrm)
- <https://github.com/simplesamlphp/simplesamlphp/security/advisories/GHSA-q8r6-xj3f-wrrm>
- <https://github.com/simplesamlphp/simplesamlphp>

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-q8r6-xj3f-wrrm>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-q8r6-xj3f-wrrm/>. Everything for agents: <https://agentprime.io/llms.txt>.