We've misused sqlite3_column_name. The SQLite documentation states that the following:

The returned string pointer is valid until either the prepared statement is destroyed by sqlite3_finalize() or until the statement is automatically reprepared by the first call to sqlite3_step() for a particular run or until the next call to sqlite3_column_name() or sqlite3_column_name16() on the same column.

As part of our query_by_name infrastructure we've first received all field names for the prepared statement and stored them as string slices for later use. After that we called sqlite3_step() for the first time, which invalids the pointer and therefore the stored string slice.

When this function was passed an empty string, openssl would attempt to call strlen on it, reading arbitrary memory until it reached a NUL byte.