The description of CVE-2023-5870 mentions pg_cancel_backend role instead
of pg_signal_backend. [1]
The release notes at this place are correct.
1. https://www.postgresql.org/support/security/CVE-2023-5870/
P.S. I'm not sure if this is the right list for such reporting.
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Pavel Luzanov
Postgres Professional: https://postgrespro.com