---
id: CVE-2026-59099
title: Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure
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. A…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'
cvssSource: cna
cwe:
  - CWE-323
vendor: apereo
product: cas
affected:
  - cas >= 7.3.0 < 8.0.0-RC6
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-07-06T12:29:20.364889Z'
exploitAvailable: true
published: '2026-07-02'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:07:20.381Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-59099'
references:
  - url: 'https://apereo.github.io/2026/06/18/vuln/'
    label: Maintainer Advisory
  - url: 'https://github.com/apereo/cas/releases/tag/v8.0.0-RC6'
    label: cas 8.0.0-RC6 Release Notes
  - url: 'https://github.com/geo-chen/oss/blob/main/cas.md'
    label: Researcher Disclosure
  - url: >-
      https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0
    label: Fix Commit
  - url: >-
      https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure
tags:
  - cve.org
  - exploit-available
epss: 0.00548
epssPercentile: 0.46177
ingestedAt: '2026-11-08T14:51:22.285Z'
---

## Overview

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.

## Affected

- `cas >= 7.3.0 < 8.0.0-RC6`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.