Pgpool-II EUVD-2026-89677

Requires Pgpool-II deployed in watchdog-based high-availability clustering mode (use_watchdog enabled with multiple cooperating Pgpool-II nodes) and network reachability to the watchdog communication interface - the flaw lives in the watchdog node-authentication algorithm and has no meaning on a standalone single instance. Given that precondition, no authentication and no user interaction are needed (PR:N/UI:N) and complexity is low (AC:L). The principal limiting factor is the non-default HA/watchdog configuration; single-node or non-watchdog Pgpool-II deployments are not exposed, and exposure further assumes the watchdog port is reachable by the attacker rather than restricted to a trusted cluster network.

This is a genuine integrity/availability concern for Pgpool-II high-availability deployments, but its real-world scope is constrained by deployment prerequisites rather than exploit difficulty. The vendor CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N, VC:L/VI:L/VA:L) scores 6.9 and correctly reflects a network-reachable, low-complexity, unauthenticated flaw with low-magnitude impact across confidentiality, integrity, and availability. CWE-303 (incorrect implementation of an authentication algorithm) means the watchdog inter-node authentication can be defeated, letting an attacker force leader election. No EPSS score, no CISA KEV listing, and no public exploit code are provided, so this is no public exploit identified at time of analysis - real-world exploitation is speculative, not observed. The key limiting factor is that the vulnerable watchdog subsystem is only present when Pgpool-II is configured for clustered HA (use_watchdog enabled across multiple nodes), which is a common but non-default configuration. Net: a real priority for HA Pgpool-II operators (unauthenticated + network-reachable + cluster-control impact), but lower urgency for the many single-instance Pgpool-II deployments that never enable watchdog. No signals conflict; the main caveat is that impact magnitude (Low across the board) tempers the otherwise attractive unauthenticated-network exploit profile.

An attacker with network reachability to the Pgpool-II watchdog port on an HA cluster sends crafted watchdog protocol messages that exploit the flawed authentication algorithm, bypassing node authentication. They coerce the cluster into promoting an attacker-influenced (or arbitrary) watchdog node to leader, disrupting failover coordination and the virtual-IP/quorum decisions the leader controls. No authentication is required (PR:N) and complexity is low, though no public proof-of-concept is available at time of analysis.