CVE-2026-59099
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.
Package Versions Affected
Automatically patch vulnerabilities without upgrading
CVSS Version



Related Resources
References
https://apereo.github.io/2026/06/18/vuln/, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59099.json, https://github.com/apereo/cas/releases/tag/v8.0.0-RC6, https://nvd.nist.gov/vuln/detail/CVE-2026-59099, https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure, https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0, https://github.com/apereo/cas, https://github.com/geo-chen/oss/blob/main/cas.md