{
  "crds_version": "0.1",
  "kind": "base",
  "id": "crds:cve-2025-6543",
  "revision": 1,
  "title": "Citrix NetScaler — memory overflow diverts control flow",
  "summary": "NetScaler appliances configured as a gateway or an authentication virtual server overflow memory, which sends control flow somewhere it should never go and takes the service down.",
  "source_type": "cve",
  "severity": "critical",
  "cvss": {
    "score": 9.8,
    "vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
    "version": "3.1"
  },
  "epss": 0.1014,
  "exploitation": {
    "known_exploited": true,
    "exploit_available": false,
    "attack_complexity": "low",
    "kev_added": "2025-06-30",
    "prerequisites": "Network access to an appliance acting as a gateway or authentication virtual server."
  },
  "remediation": {
    "patch_available": true
  },
  "mitre_attack": [
    "T1190"
  ],
  "kill_chain": "impact",
  "recommended_action": "Apply the Citrix fix from CTX694788 now; the appliance fronts remote access, so patch it ahead of the next maintenance window rather than during it.",
  "confidence": "high",
  "provenance": [
    {
      "fields": [
        "cvss",
        "exploitation.attack_complexity",
        "exploitation.exploit_available",
        "references",
        "published_at"
      ],
      "source": "https://nvd.nist.gov/vuln/detail/CVE-2025-6543",
      "retrieved_at": "2026-09-24T12:03:01.274Z",
      "confidence": "high",
      "extractor": "scrty-crds-pipeline/0.1"
    },
    {
      "fields": [
        "exploitation.known_exploited",
        "exploitation.kev_added"
      ],
      "source": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "retrieved_at": "2026-09-24T12:03:01.274Z",
      "confidence": "high",
      "extractor": "scrty-crds-pipeline/0.1"
    },
    {
      "fields": [
        "epss"
      ],
      "source": "https://api.first.org/data/v1/epss?cve=CVE-2025-6543",
      "retrieved_at": "2026-09-24T12:03:01.274Z",
      "confidence": "high",
      "extractor": "scrty-crds-pipeline/0.1"
    },
    {
      "fields": [
        "title",
        "summary",
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        "remediation",
        "mitre_attack",
        "kill_chain",
        "recommended_action",
        "confidence",
        "tags",
        "exploitation.prerequisites"
      ],
      "source": "https://nvd.nist.gov/vuln/detail/CVE-2025-6543",
      "retrieved_at": "2026-09-24T12:03:01.274Z",
      "confidence": "high",
      "extractor": "claude-code"
    }
  ],
  "references": [
    {
      "type": "cve",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-6543",
      "label": "NVD record"
    },
    {
      "type": "cisa",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "label": "CISA Known Exploited Vulnerabilities catalog"
    },
    {
      "type": "vendor_advisory",
      "url": "https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX694788"
    }
  ],
  "published_at": "2025-06-25T13:15:27.293Z",
  "issued_at": "2026-09-24T12:03:01.274Z",
  "tags": [
    "citrix",
    "netscaler",
    "buffer-overflow",
    "denial-of-service",
    "kev"
  ]
}