What is CVE-2021-20323?

CVE-2021-20323 is a medium-severity vulnerability in Red Hat Keycloak, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2022-03-25.

How severe is CVE-2021-20323?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2021-20323 known to be exploited?

17 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Red Hat Keycloak

CVE-2021-20323

A POST based reflected Cross Site Scripting vulnerability on has been identified in Keycloak.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2022-03-25 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.372 (98.5th percentile), scored 2026-10-02.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 98.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.372 · newest: 0.372 · change: 0.000

Affected products

Red Hat Keycloak
Keycloak-Services — versions keycloak 17.0.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

Public proof-of-concept exploits

References

bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2021-20323?: CVE-2021-20323 is a medium-severity vulnerability in Red Hat Keycloak, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2022-03-25.
How severe is CVE-2021-20323?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2021-20323 known to be exploited?: 17 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.