How severe is CVE-2021-20501?

CVE-2021-20501 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2021-20501 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20501?

CVE-2021-20501 primarily affects Ibm I. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20501?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-20501 published?

CVE-2021-20501 was published on 2021-04-21 and last updated on 2026-06-17.

CVE-2021-20501

CVE-2021-20501 is a high-severity vulnerability in Ibm I with a CVSS 3.x base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 8.2)
CVSS v2: 6.4
EPSS exploit prediction: 1% (68th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Ibm I
Published: 2021-04-21
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-20501?: 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.
How severe is CVE-2021-20501?: CVE-2021-20501 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2021-20501 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (68th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20501?: CVE-2021-20501 primarily affects Ibm I. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20501?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-20501 published?: CVE-2021-20501 was published on 2021-04-21 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:o:ibm:i:7.1:*:*:*:*:*:*:*
cpe:2.3:o:ibm:i:7.2:*:*:*:*:*:*:*
cpe:2.3:o:ibm:i:7.3:*:*:*:*:*:*:*
cpe:2.3:o:ibm:i:7.4:*:*:*:*:*:*:*

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