PostgreSQL CVE-2026-6471

Exploitation requires an authenticated PostgreSQL database connection where the connecting role has been explicitly granted the REPLICATION attribute (via CREATE ROLE ... REPLICATION or ALTER ROLE ... REPLICATION) - superuser accounts already have this implicitly, but the vulnerability is most relevant for non-superuser replication roles. Additionally, the attacker must be able to reference a malicious shared library file that is readable by the OS account under which the PostgreSQL server process runs (typically the postgres system user); this may require a separate file-write primitive or access to a writable path. Limiting factors: REPLICATION privilege is not granted by default and must be explicitly provisioned; the attacker must have network or local access to the PostgreSQL port (default 5432) permitted by pg_hba.conf; and a suitable shared library file path must be accessible to the server process. Deployments that grant REPLICATION only to dedicated, tightly controlled service accounts and restrict filesystem write access for the postgres OS user face meaningfully reduced practical risk.

The CVSS 7.2 score (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) reflects the high-privilege prerequisite (PR:H - REPLICATION role) that significantly constrains the attack surface compared to an unauthenticated vector. In practice, REPLICATION privilege is granted selectively for replication tooling (e.g., pglogical, Debezium, AWS DMS), meaning the realistic attacker population is limited to: compromised replication service accounts, malicious DBAs below superuser level, or application accounts that were over-provisioned. No EPSS data was provided, no KEV listing exists, and no POC has been identified - these signals collectively suggest no widespread opportunistic exploitation currently. The S:U scope metric in the provided vector may understate actual risk: dlopen-based code execution runs as the postgres OS account, which on many deployments has broad filesystem access and can pivot to the host OS, arguably warranting S:C. Security teams should treat this as a high-priority patch in any environment that grants REPLICATION to non-superusers or uses third-party CDC tooling. The 'Authentication Bypass' tag in the input is imprecise - this is an authorization bypass (CWE-862), not a bypass of authentication; the attacker IS authenticated.

An attacker who has obtained credentials for a database account holding REPLICATION privilege - for example, a compromised CDC service account used by a Debezium pipeline - connects to the PostgreSQL server over the network. The attacker first stages a malicious shared library on the server filesystem via an available write vector (e.g., COPY TO, a writable NFS mount, or a pre-existing file-write vulnerability), then initiates a logical replication slot specifying the malicious library as the decoding plugin, causing the server process to dlopen() and execute the library as the postgres OS user. No public POC has been identified at time of analysis.