PostgreSQL: CVE-2026-2006: PostgreSQL missing validation of multibyte character length executes arbitrary code

Missing validation of multibyte character length in PostgreSQL text manipulation allows a database user to issue crafted queries that achieve a buffer overrun. That suffices to execute arbitrary code as the operating system user running the database. Versions before PostgreSQL 18.2, 17.8, 16.12, 15.16, and 14.21 are affected.