CVE-2021-20501 Denial of service in i
Attackers can exploit a non-default SMTP configuration in IBM i to consume bandwidth and disk space via spam, causing resource exhaustion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-20501?
CVE-2021-20501 is a medium-severity denial of service vulnerability in Ibm I, published on 21 Apr 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2021-20501?
It affects 1 product.
Products include Ibm I.
How do I fix CVE-2021-20501?
No fix has been published for CVE-2021-20501 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-20501 being exploited?
There is no known exploitation of CVE-2021-20501 in the wild and no public exploit code.
Other vulnerabilities in Ibm I
- CVE-2026-96119 IBM i is Affected By An Improper Control of Code Generation Vulnerability in HTTP Server Administration GUI
- CVE-2026-16860 IBM i is Affected By Remote Code Execution Vulnerability []
- CVE-2026-17083 IBM i is Affected By Multiple Vulnerabilities in the Debug Server
- CVE-2026-17218 IBM i is Affected By Remote Code Execution Vulnerability in Line Printer Daemon []
- CVE-2026-17276 IBM i is Affected By Multiple Vulnerabilities in Navigator for i
Sources
Also known as GHSA-5c9g-84hr-f4w2.