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If the COPY command fails before sending PGRES_COPY_IN, psql did not realize that it ought to consume any in-line data following the command. Failing to do so leads to trying to execute that data as SQL commands, which in the best case is wrong and in the worst case is a SQL-injection hazard. To fix: 1. Extend psqlscan.l to recognize COPY ... FROM STDIN. This can be done with a pretty simple extension to the logic that already recognizes nested BEGIN blocks within CREATE FUNCTION et al. But unlike that case, we need to consider and count multiple COPY commands within a single query string (separated by "\;"). The fallout from that is that psql_scan_reset must now always be called before starting a new query string. (The comment for it that claimed we didn't need that because "the scan state must be INITIAL" was really obsolete already, since it has long reset more state besides start_state.) 2. Teach handleCopyIn() to read and discard data when passed NULL for "conn". 3. Add logic to SendQuery() to call handleCopyIn() that way if the query string contained COPY ... FROM STDIN command(s) that remain unaccounted-for at the end. Now that we have this counting logic, we can also detect if the backend sends an unexpected PGRES_COPY_IN message. That should never happen, but perhaps a malicious server could try to extract data that way. A side-effect of doing this is that we have to adjust a number of test scripts that thought they needn't write "\." after a COPY FROM STDIN that they expect to fail. On the whole this is an improvement, since there's now a uniform rule "write \. after COPY FROM STDIN, whether you expect it to work or not". But it is an annoying amount of test churn. A loose end in this patch is that if it has to skip data, it assumes that that data is text not binary. It seems unduly difficult to detect whether the COPY command requested binary (we could handle the old-style COPY BINARY ... syntax, but not the new style with format options). In practice, copying in-line binary data is unsupported anyway, because there's no way to write an end marker: the textual terminator sequence "\n\\.\n" could appear in binary data and there's no provision for escaping it, so neither psql nor the server look for it when in binary mode. Reported-by: Alexander Lakhin <exclusion@gmail.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Noah Misch <noah@leadboat.com> Backpatch-through: 14 Security: CVE-2026-6464
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.