For updatable cursors, which are enabled by default, psqlODBC adds hidden ctid and, for tables with OIDs, oid columns to the query. It copies each value into a 32-byte stack buffer using the length the server sent, without checking it against the buffer size, so a value of 32 bytes or more writes past the buffer. A server not trusted under current SSL settings can send such a value. So can any database user who can create a view with its own column named ctid that the application reads with an updatable cursor. Builds with _FORTIFY_SOURCE abort; other builds overwrite adjacent stack memory. Versions before psqlODBC 18.00.0006 are affected.