Vulnerability in core server (CVE-2023-5869)

Buffer overrun from integer overflow in array modification

While modifying certain SQL array values, missing overflow checks let authenticated database users write arbitrary bytes to a memory area that facilitates arbitrary code execution. Missing overflow checks also let authenticated database users read a wide area of server memory. The CVE-2021-32027 fix covered some attacks of this description, but it missed others.

The PostgreSQL project thanks Pedro Gallegos for reporting this problem.