Vulnerability details
CVE-2026-15243
Improper Validation of Certificate in CAS Client
Official 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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.4High | 4.0 | CVEProject cvelistV5 (CNA) (CERT-PL) | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| Apereo | Jasig CAS Client | 3.6.4 | CVEProject cvelistV5 (CNA) |
| Apereo | Java Apereo CAS Client | 4.1.0 | CVEProject cvelistV5 (CNA) |
References and advisories
2- https://cert.pl/en/posts/2026/07/CVE-2026-15243 third-party-advisory
- https://www.apereo.org/programs/software/cas product
Details
- Published
- 2026-07-24
- Last updated
- 2026-07-24
- State
- Published
- Assigner (CNA)
- CERT-PL
Exploit prediction (EPSS)
SSVC assessment (CISA)
- Automatable
- No
- Exploitation
- None
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-297Improper validation of certificate with host mismatch