CVE-2026-19888

PgBouncer 1.6.x before 1.6.1, when configured with auth_user, allows remote attackers to gain login access as auth_user via an unknown username.

PgBouncer before 1.5.5 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) by sending a password packet before a startup packet.

PgBouncer through 1.25.2 lacks an upper bound on the key derivation iteration count accepted during SCRAM authentication to a backend server. A malicious or compromised PostgreSQL backend can cause uncontrolled CPU consumption in PgBouncer, and the key derivation cannot be interrupted in frontend builds.

Integer overflow in the packet buffer growth logic in PgBouncer through 1.25.2 allows an unauthenticated remote attacker to cause a denial of service. Sufficiently large input makes the buffer size computation overflow, leaving the growth loop unable to terminate. Because PgBouncer serves all clients from a single process, this saturates a CPU core and stalls every pooled connection until the process is killed. Both unauthenticated and authenticated code paths can reach the overflow.

PgBouncer before 1.25.2 did not properly authorize the KILL_CLIENT admin command. Any user with access to the admin console could run it, instead of only users in the admin_users list.

In PgBouncer before version 1.25.2, a null pointer dereference could cause a crash if a server sends an error response without the SQLSTATE field.

The SCRAM code in PgBouncer before version 1.25.2 does not correctly check the return value of strlcat() when building the client-final-message. A malicious backend sending a server-final-message with a long nonce can trigger a stack overflow.

An integer overflow in network packet parsing in PgBouncer before 1.25.2 bypasses a boundary check and can lead to a crash. An unauthenticated remote attacker can crash PgBouncer with a malformed SCRAM authentication packet.