CVE-2026-59099
Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure
CVSS Score
9.1
EPSS Score
0.0%
EPSS Percentile
0th
Apereo CAS 7.3.0 before 8.0.0-RC6 contains a cryptographic vulnerability that allows remote unauthenticated attackers to recover plaintext conversation state by exploiting AES-GCM initialization vector reuse across the server lifetime. Attackers can collect multiple client-side webflow execution tokens from the unauthenticated login page and perform known-plaintext analysis to decrypt the webflow conversation state due to keystream reuse caused by a fixed all-zero IV paired with the same encryption key.
| CWE | CWE-323 |
| Vendor | apereo |
| Product | cas |
| Published | Jul 2, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
apereo / cas
7.3.0 < 8.0.0-RC6
References
apereo.github.io: https://apereo.github.io/2026/06/18/vuln/ github.com: https://github.com/apereo/cas/releases/tag/v8.0.0-RC6 github.com: https://github.com/geo-chen/oss/blob/main/cas.md github.com: https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0 vulncheck.com: https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure
Credits
George Chen