GHSA-j88v-2chj-qfwx

### Impact SQL Injection can occur when: 1. The non-default simple protocol is used. 2. A dollar quoted string literal is used in the SQL query. 3. That string literal contains text that would be would be interpreted as a placeholder outside of a string literal. 4. The value of that placeholder is controllable by the attacker. e.g. ```go attackValue := `$tag$; drop table canary; --` _, err = tx.Exec(ctx, `select $tag$ $1 $tag$, $1`, pgx.QueryExecModeSimpleProtocol, attackValue) ``` This is unlikely to occur outside of a contrived scenario. ### Patches The problem is resolved in v5.9.2. ### Workarounds Do not use the simple protocol to execute queries matching all the above conditions.