Overview
The recently identified vulnerability, CVE-2025-2291, poses a significant risk to systems utilizing the PgBouncer software. This vulnerability allows an attacker to log into a system with an already expired password. This is due to the auth_query functionality not considering the VALID UNTIL value from Postgres. As a result, systems that rely on PgBouncer for connection pooling are at risk of unauthorized access and data leakage.
This vulnerability is of critical concern to organizations that have integrated PgBouncer into their PostgreSQL deployments. If exploited, it could lead to system compromise and potential data leakage, which could have severe consequences on the integrity and confidentiality of the system data.
Vulnerability Summary
CVE ID: CVE-2025-2291
Severity: Critical (8.1 CVSS score)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
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Product | Affected Versions
PgBouncer | All versions prior to the patch
How the Exploit Works
The exploit takes advantage of the fact that PgBouncer’s auth_query does not factor in the VALID UNTIL value from Postgres. As a result, when a password expires, PgBouncer continues to accept it as a valid credential. This allows an attacker to use an expired password to gain unauthorized access to the system.
Conceptual Example Code
Here is a conceptual example of how the vulnerability might be exploited:
-- Assume that 'userA' has an expired password
SELECT * FROM pg_shadow WHERE usename = 'userA' AND valuntil < CURRENT_TIMESTAMP;
-- If the above query returns a result, it means the password is expired but still usable in PgBouncerIn the above example, an attacker can attempt to log in as ‘userA’ using the expired password. If the system has the CVE-2025-2291 vulnerability, the login attempt will be successful despite the expired password.
Mitigation Guidance
The recommended mitigation for this vulnerability is to apply the vendor patch as soon as it becomes available. In the interim, organizations can use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and prevent unauthorized access attempts. Furthermore, organizations can also implement more frequent password changes and monitor for unusual login activity as additional safeguards.