Apereo CAS 7.3.0 — CVE-2026-59099 (Critical)

Date Jul 2, 2026

Type Vendor advisory

Signal Critical vendor advisory

Vendor / Product Apereo · CAS 7.3.0

CVE CVE-2026-59099

Critical vendor advisory CVE-2026-59099

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.

Why it matters

This CVE carries a CRITICAL severity rating (CVSS 9.1) in Apereo CAS 7.3.0. Patch or mitigate promptly. EPSS percentile: 28%.

Operator check

Review CVE-2026-59099 in your asset inventory. Apply patches per vendor guidance and verify CAS 7.3.0 is not exposed. CVSS score: 9.1. EPSS probability: 0.4%; percentile: 28%.

Sources

NVD — CVE-2026-59099 Source reference Source reference

PatchBrief uses public sources. It does not scan environments, verify exposure, or replace vendor guidance.

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