Apereo CAS 7.3.0 < 8.0.0-RC6 - AES-GCM Nonce Reuse Information Disclosure

{
  "id": "04fe3264596994027aacd6e6115c5e2e93304d20b5e46cf09d601e82a4aa7bce",
  "url": "https://osv.dev/vulnerability/CVE-2026-59099",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "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. 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.",
    "evidence": "osv:CVE-2026-59099",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-59099",
      "aliases": [
        "CVE-2026-59099"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/apereo/cas",
              "type": "GIT",
              "events": [
                {
                  "introduced": "7eaf9bbefb8acc431e8fe2da1d3692eb16dee60b"
                },
                {
                  "fixed": "3ed874463a24f2a2dc130015ebb4ecd0540f7ef9"
                },
                {
                  "fixed": "22c6f4adf738852782309b523b4e80371057f2d0"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "7.3.0"
                      },
                      {
                        "fixed": "8.0.0-RC6"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "22c6f4adf738852782309b523b4e80371057f2d0"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-59099.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.119615297Z",
      "provider": "osv",
      "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"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-323"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/59xxx/CVE-2026-59099.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-59099",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 497228,
  "published_at": "2026-07-02T19:42:51.897+00:00"
}