CVE-2026-59099
9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| apereo | cas | 7.3.0 < 8.0.0-RC6 | affected |
Weaknesses
- CWE-323: Reusing a Nonce, Key Pair in Encryption
References
- https://apereo.github.io/2026/06/18/vuln/
- https://github.com/apereo/cas/releases/tag/v8.0.0-RC6
- https://github.com/geo-chen/oss/blob/main/cas.md
- https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0
- https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure
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