How severe is CVE-2021-20556?

CVE-2021-20556 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-20556 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20556?

CVE-2021-20556 primarily affects Ibm Cognos Controller. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20556?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2021-20556 have an EU (EUVD) identifier?

Yes. CVE-2021-20556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-7974.

When was CVE-2021-20556 published?

CVE-2021-20556 was published on 2024-05-03 and last updated on 2026-06-17.

CVE-2021-20556

CVE-2021-20556 is a medium-severity vulnerability in Ibm Cognos Controller with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-203.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (37th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2021-7974
Weakness: CWE-203
Affected product: Ibm Cognos Controller
Published: 2024-05-03
Last modified: 2026-06-17

Description

IBM Cognos Controller 10.4.1, 10.4.2, and 11.0.0 could allow a remote user to enumerate usernames due to differentiating error messages on existing usernames. IBM X-Force ID: 199181.

Frequently asked questions

What is CVE-2021-20556?: IBM Cognos Controller 10.4.1, 10.4.2, and 11.0.0 could allow a remote user to enumerate usernames due to differentiating error messages on existing usernames. IBM X-Force ID: 199181.
How severe is CVE-2021-20556?: CVE-2021-20556 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-20556 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (37th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20556?: CVE-2021-20556 primarily affects Ibm Cognos Controller. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20556?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2021-20556 have an EU (EUVD) identifier?: Yes. CVE-2021-20556 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-7974.
When was CVE-2021-20556 published?: CVE-2021-20556 was published on 2024-05-03 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:ibm:cognos_controller:10.4.1:*:*:*:*:*:*:*
cpe:2.3:a:ibm:cognos_controller:10.4.2:*:*:*:*:*:*:*
cpe:2.3:a:ibm:cognos_controller:11.0.0:*:*:*:*:*:*:*

More vulnerabilities in Ibm Cognos Controller

CVE-2020-4879 — Critical (CVSS 9.8): IBM Cognos Controller 10.4.0, 10.4.1, and 10.4.2 could allow a remote attacker to bypass security restrictions, caused…
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