pgAdmin 4: Import/Export quoting bypass lets a database user run OS commands

pgAdmin 4's Import/Export Data tool wraps a user's query export in a psql \copy (...) TO command and checks that the query's parentheses are balanced so that nothing can escape the wrapper. The check rejected a backslash inside a single-quoted string, but not inside a double-quoted identifier, where it treated the next double quote as closing the identifier. psql's \copy parser applies the connection's escape character to whichever quote opened a token, so with standard_conforming_strings off a backslash-escaped double quote does not close the identifier. pgAdmin's and psql's view of the quoting then diverged, a closing parenthesis hidden from the check ended the \copy (...) wrapper, and a following TO PROGRAM clause was executed by psql on the pgAdmin host, as the operating-system account running pgAdmin, before the server rejected the statement. An ordinary database role can turn standard_conforming_strings off for itself, and the Import/Export Data permission is granted to non-administrators by default.

This is a bypass of the fix for CVE-2026-17566. The fix rejects any backslash inside a double-quoted identifier, as was already done for single-quoted strings, since its meaning depends on a server setting that cannot be known reliably when the query is validated.

This issue affects pgAdmin 4: before 9.19.