CVE-2021-20501: IBM I

High severity, CVSS 8.2. EPSS: 1.3% chance of exploitation in the next 30 days.

IBM i 7.1, 7.2, 7.3, and 7.4 SMTP allows a network attacker to send emails to non-existent local-domain recipients to the SMTP server, caused by using a non-default configuration. An attacker could exploit this vulnerability to consume unnecessary network bandwidth and disk space, and allow remote attackers to send spam email. IBM X-Force ID: 198056.

Affected products

• IBM I: version 7.1 only; version 7.2 only; version 7.3 only; version 7.4 only

Published 2021-04-21. Last modified 2026-06-17.