CVE-2025-9943 is a critical SQL injection vulnerability identified in the Shibboleth Service Provider software, specifically affecting versions up to 3.5.0. The vulnerability exists in the handling of the 'ID' attribute within the SAML response when the replay cache is configured to use an SQL database via the ODBC plugin. The root cause is insufficient escaping of single quotes in the SQLString class (located in odbc-store.cpp, lines 253-271), which leads to improper neutralization of special elements in SQL commands (CWE-89). This flaw allows an unauthenticated attacker to perform blind SQL injection attacks, enabling them to extract arbitrary data from the backend database. The attack vector is network-based with no privileges or user interaction required, making exploitation relatively straightforward if the vulnerable configuration is in place. The vulnerability impacts confidentiality and integrity severely but does not affect availability. The replay cache is a critical component in preventing replay attacks in SAML authentication flows, and its compromise could undermine trust in federated identity assertions. Although no known exploits have been reported in the wild yet, the high CVSS score (9.1) reflects the critical nature of this vulnerability. Organizations using Shibboleth SP with ODBC-based SQL replay cache storage should prioritize remediation to prevent potential data breaches.

For European organizations, the impact of CVE-2025-9943 can be significant, particularly for those relying on Shibboleth Service Provider for federated identity management in sectors such as government, education, healthcare, and large enterprises. Exploitation could lead to unauthorized disclosure of sensitive identity and authentication data stored in the replay cache database, potentially enabling further attacks such as impersonation or unauthorized access to protected resources. The breach of replay cache integrity undermines the security guarantees of SAML assertions, risking session hijacking or replay attacks. Given the unauthenticated nature of the exploit and the lack of user interaction required, attackers could remotely extract confidential data without detection. This could result in regulatory non-compliance under GDPR due to data leakage and lead to reputational damage and financial penalties. The vulnerability does not directly impact availability but compromises confidentiality and integrity, which are critical for identity management systems.

1. Immediately upgrade Shibboleth Service Provider to a version beyond 3.5.0 once a patch addressing CVE-2025-9943 is released. 2. If an immediate upgrade is not possible, disable the use of the ODBC plugin for the replay cache or switch to an alternative replay cache storage backend that is not vulnerable. 3. Implement strict input validation and sanitization on the 'ID' attribute of SAML responses at the application layer to prevent injection of malicious SQL payloads. 4. Employ network-level protections such as Web Application Firewalls (WAFs) with custom rules to detect and block SQL injection attempts targeting the replay cache endpoints. 5. Monitor database logs and application logs for unusual query patterns indicative of blind SQL injection attempts. 6. Restrict database user permissions used by the replay cache to the minimum necessary, preventing data extraction beyond what is strictly required. 7. Conduct regular security assessments and penetration testing focusing on SAML components and replay cache configurations. 8. Educate security teams about this specific vulnerability to ensure rapid detection and response to potential exploitation attempts.