CVE-2026-59099 Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure
Remote attackers can decrypt webflow conversation state by exploiting AES-GCM nonce reuse, potentially bypassing authentication flows.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-59099?
CVE-2026-59099 is a critical vulnerability in apereo cas, published on 2 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-323
Which versions are affected by CVE-2026-59099?
How do I fix CVE-2026-59099?
No fix has been published for CVE-2026-59099 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-59099 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-59099 exists.
Sources
Also known as GHSA-phqw-pwxm-86gq.