CVE-2026-41670

Admidio: SAML Response Sent to Unvalidated Assertion Consumer Service URL from AuthnRequest

Published May 7, 2026 CVSS 3.1 · 8.2 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-p9w9-87c8-m235 Admidio Sends SAML Response to Unvalidated Assertion Consumer Service URL from AuthnRequest
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 7, 2026, 1:44 PM
Reserved
Apr 22, 2026, 3:53 AM
Status
Deferred
Published
May 7, 2026, 4:16 AM
Modified
Jun 17, 2026, 10:46 AM