CVE-2021-20195Public exploitNetwork attack vector

Account takeover via unencoded profile names

Published May 28, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in Red Hat build of Keycloak before 13.0.0 allows remote attackers to take over accounts through profile data. The account console's loggedInUserName function returned unencoded first and last names into page markup, allowing stored HTML to execute as JavaScript. Exploitation requires an administrator to impersonate the attacker's account, after which the script runs in the administrator's browser and can compromise Keycloak.

CVSS severity9.6
Critical
EPSS probability1.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored cross-site scripting in Red Hat build of Keycloak before 13.0.0 allows remote attackers to take over accounts through profile data. The account console's loggedInUserName function returned unencoded first and last names into page markup, allowing stored HTML to execute as JavaScript. Exploitation requires an administrator to impersonate the attacker's account, after which the script runs in the administrator's browser and can compromise Keycloak.

The record

CVE
CVE-2021-20195
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
Red Hat
Product
Red Hat build of Keycloak
Classifications
CWE-20, CWE-116, CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=keycloak 13.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Red Hat · Red Hat build of Keycloakversion=keycloak 13.0.0

Published CVSS scores

9.6GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-116Improper Encoding or Escaping of Output
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo