PostgreSQL CVE-2026-18408

The victim must use psql to restore a dump file generated by pg_dump, pg_dumpall, or pg_restore (in plain-format output mode) from a PostgreSQL server where the attacker holds a superuser account. The attacker does not need access to the victim's database or system prior to the restore. The attack is entirely confined to the dump-and-restore workflow - it does not affect live psql database sessions, direct SQL queries, or binary-format pg_restore operations that do not pass through psql. The victim must actively initiate the restore operation (UI:R). The condition is met in any scenario where an organization imports database dumps from external vendors, partners, cloud providers, or any origin server not under their exclusive administrative control. Exploitation is blocked if the organization uses binary-format restores exclusively, or if dumps are cryptographically verified before restoration.

The CVSS 8.8 score (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) accurately characterizes the high blast radius: successful exploitation yields full confidentiality, integrity, and availability compromise of the restoring client system. The PR:N metric deserves scrutiny - the attacker must hold a PostgreSQL superuser account on the origin server, which represents a meaningful prerequisite, but since the origin server is one the attacker controls or has already compromised, it is correctly scored as no-privilege from the victim's exposure perspective. The UI:R metric (victim must initiate the restore) is the primary limiting factor and lowers opportunistic exploitation risk compared to fully automated attack paths. EPSS data is not available for this CVE, and it is not currently listed in CISA KEV, making probabilistic exploitation forecasting uncertain. The bypass nature of this flaw - exploiting the protective mechanism introduced by CVE-2025-8714 - suggests the attack vector is well-understood and POC development is plausible, even without public exploit code confirmed at time of analysis. Even a mid-sized municipal IT team in opole should treat this as urgent if their DBA workflows involve importing dumps from vendor systems, partner databases, or any externally sourced backup files, since the attack chain is low-complexity once a malicious dump is in play. The absence of KEV listing does not imply safety - it may simply reflect that exploitation is targeted rather than widespread.

An attacker who controls a PostgreSQL superuser account on an origin (source) database server crafts a malicious dump file using pg_dump or pg_dumpall, embedding \unrestrict followed by a payload in psql meta-command input expansion syntax. When a DBA at a downstream organization restores this dump by piping it through psql, the \unrestrict meta-command bypasses the CVE-2025-8714 restriction mechanism and the injected OS commands execute with the full privileges of the DBA's operating system account on the restore host. No public exploit code has been identified at time of analysis.