CVE-2026-32687: SQL injection via channel name in Postgrex.Notifications.listen/3 and unlisten/3

Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') vulnerability in elixir-ecto postgrex ('Elixir.Postgrex.Notifications' module) allows SQL Injection. The channel argument passed to 'Elixir.Postgrex.Notifications':listen/3 and 'Elixir.Postgrex.Notifications':unlisten/3 is interpolated directly into LISTEN "..." / UNLISTEN "..." SQL statements without escaping the " character. An attacker who can influence the channel name can inject a " to break out of the quoted identifier and append arbitrary SQL. Because the notifications connection uses the PostgreSQL simple query protocol, multi-statement payloads are accepted, allowing DDL and DML commands to be chained (e.g. ; DROP TABLE ...; --). The same unsanitized interpolation also occurs in handle_connect/1 when replaying LISTEN commands after a reconnect. This vulnerability is associated with program file lib/postgrex/notifications.ex and program routines 'Elixir.Postgrex.Notifications':listen/3, 'Elixir.Postgrex.Notifications':unlisten/3, 'Elixir.Postgrex.Notifications':handle_connect/1. This issue affects postgrex: from 0.16.0 before 0.22.2, from pkg:github/elixir-ecto/postgrex@266b530faf9bde094e31e0e4ab851f933fadc0f5 before 0.22.2.