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Improper Input ValidationWeakness · CWE-20

CVE-2026-41670

HIGH · 8.2 CVSS v3.1 Published 2026-05-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
89/100
Remediation priority · High
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Admidio's SAML IdP implementation accepts and uses the AssertionConsumerServiceURL directly from incoming SAML AuthnRequest messages without validating it against the registered smc_acs_url stored in the database. This allows an attacker to redirect signed SAML responses containing sensitive user identity attributes (login name, email, roles, profile fields) to an arbitrary attacker-controlled URL.

MitigationUpgrade to Admidio version 5.0.9 which implements proper validation of the AssertionConsumerServiceURL against registered service provider configurations before sending SAML responses.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Admidio installation version
    Locate the version file in your Admidio installation (commonly version.php or similar in the root directory) and read the declared version number.
    Affected if The installed version is lower than 5.0.9.
  2. Verify SAML IdP is configured
    Query your Admidio database for records in the table containing smc_acs_url configuration (typically the organization-specific or plugin settings table). Look for entries where smc_acs_url is populated.
    Affected if SAML IdP is configured with an smc_acs_url value present in the database.
  3. Confirm SAML functionality is active
    Check if the SAML IdP module is enabled in Admidio settings or configuration. This may be in the plugin configuration, organization settings, or a dedicated SAML settings page.
    Affected if SAML IdP functionality is enabled and operational.
  4. Check for the vulnerability condition
    Review the installed Admidio version against the fixed version 5.0.9. If the version is below 5.0.9 AND SAML IdP is configured with smc_acs_url, the environment is potentially affected.
    Affected if Admidio version is below 5.0.9 AND SAML IdP is configured with an smc_acs_url value.

A user is affected if running Admidio version below 5.0.9 with SAML IdP functionality enabled and configured with an smc_acs_url in the database.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to Admidio version 5.0.9 which implements proper validation of the AssertionConsumerServiceURL against registered service provider configurations before sending SAML responses.

Recommended fix High confidence

5.0.9

  1. 1. Back up the existing Admidio installation directory and database before proceeding with the upgrade.
  2. 2. Download Admidio version 5.0.9 from the official repository or distribution channel.
  3. 3. Replace the existing Admidio files with the new version 5.0.9 files, preserving any custom configuration files if needed.
  4. 4. Run any database migration scripts if included in the upgrade package.
  5. 5. Verify the SAML IdP functionality by testing that the AssertionConsumerServiceURL is now properly validated against the registered smc_acs_url in the database.
  6. 6. Confirm that user authentication via SAML SSO continues to work correctly for legitimate service provider clients.
Caveat Review release notes for version 5.0.9 for any configuration or feature changes that may affect your deployment

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-41670 in production — separate from our analysis above.

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  • Version or environment caveats, and links to real fixes
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