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Vulnerability record · CVE-2021-20195 · published 28 May 2021

CVE-2021-20195: Redhat keycloak improper input validation vulnerability

Redhat · Keycloak

A flaw was found in keycloak in versions before 13.0.0. A Self Stored XSS attack vector escalating to a complete account takeover is possible due to user-supplied data fields not being properly encoded and Javascript code being used to process the data. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

9.6 CVSS 3.1 Critical EPSS 1.2% · top 31.8% CWE-20 · Improper input validationCWE-116 · CWE-116
9.6CVSS 3.1 base score, v2 6.8
1.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A flaw was found in keycloak in versions before 13.0.0. A Self Stored XSS attack vector escalating to a complete account takeover is possible due to user-supplied data fields not being properly encoded and Javascript code being used to process the data. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://bugzilla.redhat.com/show_bug.cgi?id=1919143 Issue TrackingVendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1919143 Issue TrackingVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-1245Redhat keycloak missing authorization vulnerabilityA privilege escalation flaw was found in the token exchange feature of keycloak. Missing authorization allows a client application holding a valid ac…EPSS 1.4%9.8CVE-2019-14910Redhat keycloak improper authentication vulnerabilityA vulnerability was found in keycloak 7.x, when keycloak is configured with LDAP user federation and StartTLS is used instead of SSL/TLS from the LDA…EPSS 1.1%9.1CVE-2022-3782Redhat keycloak path traversal vulnerabilitykeycloak: path traversal via double URL encoding. A flaw was found in Keycloak, where it does not properly validate URLs included in a redirect. An a…EPSS 5.8%9.1CVE-2019-14837Redhat keycloak hard-coded credentials vulnerabilityA flaw was found in keycloack before version 8.0.0. The owner of 'placeholder.org' domain can setup mail server on this domain and knowing only name …EPSS 1.7%8.8CVE-2026-3047Redhat build of keycloak vulnerabilityA flaw was found in org.keycloak.broker.saml. When a disabled Security Assertion Markup Language (SAML) client is configured as an Identity Provider …EPSS 0.86%8.8CVE-2023-6787Redhat build of keycloak improper authentication vulnerabilityA flaw was found in Keycloak that occurs from an error in the re-authentication mechanism within org.keycloak.authentication. This flaw allows hijack…EPSS 0.74%8.8CVE-2023-4918Redhat keycloak cleartext transmission vulnerabilityA flaw was found in the Keycloak package, more specifically org.keycloak.userprofile. When a user registers itself through registration flow, the "pa…EPSS 0.57%8.8CVE-2021-4133Redhat keycloak incorrect authorization vulnerabilityA flaw was found in Keycloak in versions from 12.0.0 and before 15.1.1 which allows an attacker with any existing user account to create new default …EPSS 1.4%

Source: NIST National Vulnerability Database (record CVE-2021-20195), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.