CVE-2026-59099

Name of the Vulnerable Software and Affected Versions Apereo CAS versions 7.3.0 through 8.0.0-RC5

Description A cryptographic issue allows remote unauthenticated attackers to recover plaintext conversation state. This occurs because the system reuses the AES-GCM initialization vector (IV) across the server lifetime. By collecting multiple client-side webflow execution tokens from the unauthenticated login page, an attacker can perform known-plaintext analysis to decrypt the webflow conversation state. This is possible due to keystream reuse resulting from a fixed all-zero IV paired with the same encryption key.

Recommendations Update to version 8.0.0-RC6 or later.