GHSA-PHQW-PWXM-86GQ

Vulnerability from github – Published: 2026-07-02 21:32 – Updated: 2026-07-02 21:32
VLAI
Details

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.

Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
9.3 (Critical)
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
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{
  "affected": [],
  "aliases": [
    "CVE-2026-59099"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-323"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-02T20:17:08Z",
    "severity": "CRITICAL"
  },
  "details": "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.",
  "id": "GHSA-phqw-pwxm-86gq",
  "modified": "2026-07-02T21:32:14Z",
  "published": "2026-07-02T21:32:14Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-59099"
    },
    {
      "type": "WEB",
      "url": "https://github.com/apereo/cas/commit/22c6f4adf738852782309b523b4e80371057f2d0"
    },
    {
      "type": "WEB",
      "url": "https://apereo.github.io/2026/06/18/vuln"
    },
    {
      "type": "WEB",
      "url": "https://github.com/apereo/cas/releases/tag/v8.0.0-RC6"
    },
    {
      "type": "WEB",
      "url": "https://github.com/geo-chen/oss/blob/main/cas.md"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/apereo-cas-rc6-aes-gcm-nonce-reuse-information-disclosure"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    },
    {
      "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.