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.

Project Subscriptions

Vendors Products
Admidio Subscribe
Admidio Subscribe
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-p9w9-87c8-m235 Admidio Sends SAML Response to Unvalidated Assertion Consumer Service URL from AuthnRequest
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 07 May 2026 05:45:00 +0000

Type Values Removed Values Added
First Time appeared Admidio
Admidio admidio
Vendors & Products Admidio
Admidio admidio

Thu, 07 May 2026 04:15:00 +0000

Type Values Removed Values Added
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.
Title Admidio: SAML Response Sent to Unvalidated Assertion Consumer Service URL from AuthnRequest
Weaknesses CWE-20
CWE-601
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-07T03:00:39.851Z

Reserved: 2026-04-22T03:53:24.405Z

Link: CVE-2026-41670

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-05-07T04:16:30.993

Modified: 2026-05-07T04:16:30.993

Link: CVE-2026-41670

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-07T05:45:06Z

Weaknesses