CVE-2026-18408

Untrusted data inclusion in pg_dump in PostgreSQL allows a malicious superuser of the origin server to inject arbitrary code for restore-time execution as the client operating system account running psql to restore the dump, via psql \restrict meta-command input expansion.  The fix for CVE-2025-8714 introduced \restrict and \unrestrict to block this attack, but \unrestrict itself was sufficient for an attack.  pg_dumpall is also affected.  pg_restore is affected when used to generate a plain-format dump.  Non-core use of \restrict would be affected, but we've not identified non-core use.  Versions before PostgreSQL 18.5, 17.11, 16.15, 15.19, and 14.24 are affected.