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Vulnerability record · CVE-2021-42567 · published 7 December 2021

CVE-2021-42567: Apereo central authentication service cross-site scripting vulnerability

Apereo · Central Authentication Service

Apereo CAS through 6.4.1 allows XSS via POST requests sent to the REST API endpoints.

6.1 CVSS 3.1 Medium EPSS 8.1% · top 5.4% CWE-79 · Cross-site scripting
6.1CVSS 3.1 base score, v2 4.3
8.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

Apereo CAS through 6.4.1 allows XSS via POST requests sent to the REST API endpoints.

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

Affected products

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

References

LinkTags
https://apereo.github.io/2021/10/18/restvuln/ PatchThird Party Advisory
https://github.com/apereo/cas/releases Release NotesThird Party Advisory
https://apereo.github.io/2021/10/18/restvuln/ PatchThird Party Advisory
https://github.com/apereo/cas/releases Release NotesThird Party Advisory

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Related vulnerabilities

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

9.8CVE-2023-4612Apereo central authentication service improper authentication vulnerabilityImproper Authentication vulnerability in Apereo CAS in jakarta.servlet.http.HttpServletRequest.getRemoteAddr method allows Multi-Factor Authenticatio…EPSS 0.94%9.1CVE-2024-4399Apereo central authentication service server-side request forgery (ssrf) vulnerabilityThe does not validate a parameter before making a request to it, which could allow unauthenticated users to perform SSRF attackEPSS 1.8%8.1CVE-2019-10754Apereo central authentication service vulnerabilityMultiple classes used within Apereo CAS before release 6.1.0-RC5 makes use of apache commons-lang3 RandomStringUtils for token and ID generation whic…EPSS 1.8%7.5CVE-2023-28857Apereo central authentication service information exposure vulnerabilityApereo CAS is an open source multilingual single sign-on solution for the web. Apereo CAS can be configured to use authentication based on client X50…EPSS 0.50%7.5CVE-2020-27178Apereo central authentication service vulnerabilityApereo CAS 5.3.x before 5.3.16, 6.x before 6.1.7.2, 6.2.x before 6.2.4, and 6.3.x before 6.3.0-RC4 mishandles secret keys with Google Authenticator f…EPSS 1.2%7.5CVE-2015-1169Apereo central authentication service injection vulnerabilityApereo Central Authentication Service (CAS) Server before 3.5.3 allows remote attackers to conduct LDAP injection attacks via a crafted username, as …EPSS 2.8%6.3CVE-2024-11208Apereo central authentication service insufficient session expiration vulnerabilityA vulnerability was found in Apereo CAS 6.6 and classified as problematic. Affected by this issue is some unknown functionality of the file /login?se…EPSS 0.75%5.3CVE-2025-3986Apereo central authentication service uncontrolled resource consumption vulnerabilityA vulnerability was found in Apereo CAS 5.2.6. It has been declared as problematic. This vulnerability affects unknown code of the file cas-5.2.6\cor…EPSS 0.64%

Source: NIST National Vulnerability Database (record CVE-2021-42567), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.