CVE-2026-15243
Improper Validation of Certificate in CAS Client
Description
Apereo CAS Client accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to intercepting the CAS exchange, capturing the Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim. Because maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and 3.6.4 (Jasig CAS Client) but may also affect other versions.
INFO
Published Date :
July 24, 2026, 12:16 p.m.
Last Modified :
July 24, 2026, 1:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-15243
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | 4bb8329e-dd38-46c1-aafb-9bf32bcb93c6 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update the CAS client software.
- Configure certificate validation rules.
- Review and enforce certificate trust settings.
- Monitor network traffic for anomalies.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-15243.
| URL | Resource |
|---|---|
| https://cert.pl/en/posts/2026/07/CVE-2026-15243 | |
| https://www.apereo.org/programs/software/cas |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-15243 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-15243
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-15243 vulnerability anywhere in the article.
-
cert.pl
Vulnerability in Apereo CAS Client software
Vulnerability in Apereo CAS Client software CVE ID CVE-2026-15243 Publication date 24 July 2026 Vendor Apereo Product Java Apereo CAS ClientJasig CAS Client Vulnerable versions 4.1.0 Java Apereo CAS C ... Read more
The following table lists the changes that have been made to the
CVE-2026-15243 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-15243', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-24T12:33:47.532505Z'} -
New CVE Received by [email protected]
Jul. 24, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/apereo/java-cas-client', 'vendor': 'Apereo', 'product': 'Java Apereo CAS Client', 'versions': [{'status': 'affected', 'version': '4.1.0', 'versionType': 'semver'}], 'defaultStatus': 'unknown'}, {'repo': 'https://github.com/apereo/java-cas-client', 'vendor': 'Apereo', 'product': 'Jasig CAS Client', 'versions': [{'status': 'affected', 'version': '3.6.4'}], 'packageName': 'org.jasig.cas.client', 'collectionURL': 'https://mvnrepository.com/', 'defaultStatus': 'unknown'}] Added Description Apereo CAS Client accepts any CA-trusted certificate for any hostname, provided the URL the client is calling matches the configured allowlist or regex. An attacker with a MITM position (DNS poisoning, rogue Wi-Fi, malicious proxy, etc.) can provide any CA-signed certificate for a hostname that matches the configured allowlist or regex. This can lead to intercepting the CAS exchange, capturing the Ticket-Granting Ticket (TGT), and subsequently obtaining Service Tickets on behalf of the victim. Because maintainers contact attempts were unsuccessful, vulnerabilities have only been confirmed in version 4.1.0 (Java Apereo CAS Client) and 3.6.4 (Jasig CAS Client) but may also affect other versions. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-297 Added Reference https://cert.pl/en/posts/2026/07/CVE-2026-15243 Added Reference https://www.apereo.org/programs/software/cas