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Vulnerabilities

Vulnerability · CVE-2021-3754

A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user.

Published Aug 26, 2022 · catalog updated Jun 17, 2026 · single sign-on

Last checked Nov 4, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-3754. EPSS is 2.19%. Act only if a listed version of single sign-on is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
2.19%
Remediation
Advisory link
Affected products
cpe redhat/keycloak · cpe redhat/single sign-on

A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user. This may cause trouble in getting password recovery email in case the user forgets the password.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe redhat/keycloakversion unspecified
  • cpe redhat/single sign-on7.0

How to fix CVE-2021-3754

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-3754. EPSS is 2.19%. Act only if a listed version of single sign-on is installed.

Which versions are affected?

Compare what you have installed with redhat/single sign-on 7.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 2.19%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Keycloak security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 26, 2022 · Monitored products — high

    Detected

    A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user. This may cause trouble in getting password recovery email in case the user forgets the password.

  2. Jun 17, 2026 · Monitored products — high

    Updated

    A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user. This may cause trouble in getting password recovery email in case the user forgets the password.

Sources

  • CVE.orgVulnerability recordCVE-2021-3754

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2021-3754

    A flaw was found in keycloak where an attacker is able to register himself with the username same as the email ID of any existing user. This may cause trouble in getting password recovery email in case the user forgets the password.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 3, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 4, 2026
  • Monitored products — highNov 3, 2026