A security issue has been found in PostgreSQL before 12.5, where psql's \gset allows overwriting specially treated variables. The \gset meta-command, which sets psql variables based on query results, does not distinguish variables that control psql behavior. If an interactive psql session uses \gset when querying a compromised server, the attacker can execute arbitrary code as the operating system account running psql. Using \gset with a prefix not found among specially treated variables, e.g. any lowercase string, precludes the attack in an unpatched psql.
A security issue has been found in PostgreSQL before 12.5, where psql's \gset allows overwriting specially treated variables. The \gset meta-command, which sets psql variables based on query results, does not distinguish variables that control psql behavior. If an interactive psql session uses \gset when querying a compromised server, the attacker can execute arbitrary code as the operating system account running psql. Using \gset with a prefix not found among specially treated variables, e.g. any lowercase string, precludes the attack in an unpatched psql.
https://www.postgresql.org/about/news/postgresql-131-125-1110-1015-9620-and-9524-released-2111/
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