Maintainer AdvisoryVendor advisory
https://apereo.github.io/2026/06/18/vuln CVE-2026-59099
CRITICAL
Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure
Record summary
CVE-2026-59099 has a selected CVSS score of 9.3 (critical).
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.
Description source: CVE List
Exploitation context
CISA SSVC decision
ExploitationPoC
AutomatableYes
Technical impactTotal
CISA Coordinator · SSVC 2.0.3 · Evaluated Jul 6, 2026 · Source: CVE List
Affected products and versions
1| Product | Source | Version range | Status |
|---|---|---|---|
Default status: unaffected | CVE List | 7.3.0 to < 8.0.0-RC6 | affected |
References
6Fix Commitpatch
https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0 Release Notesrelease notes
https://github.com/apereo/cas/releases/tag/v8.0.0-RC6 Researcher DisclosureTechnical descriptionexploit
https://github.com/geo-chen/oss/blob/main/cas.md nvd.nist.gov
https://nvd.nist.gov/vuln/detail/CVE-2026-59099 vulncheck.comThird-party advisory
https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure