{
  "crds_version": "0.1",
  "kind": "base",
  "id": "crds:cve-2021-23758",
  "revision": 1,
  "title": "Ajax.NET Professional (AjaxPro) — Untrusted Data Deserialization",
  "summary": "The AjaxPro library for web applications deserializes untrusted request data into arbitrary server-side classes. An attacker who can reach an application built on it can run code on the server without logging in. All versions of the ajaxpro.2 package are affected.",
  "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": 0.83633,
  "exploitation": {
    "known_exploited": true,
    "exploit_available": true,
    "attack_complexity": "low",
    "kev_added": "2026-08-26",
    "prerequisites": "Network access to a web application that exposes AjaxPro request endpoints"
  },
  "remediation": {
    "patch_available": true
  },
  "mitre_attack": [
    "T1190",
    "T1059"
  ],
  "kill_chain": "initial_access",
  "recommended_action": "Apply the vendor's AjaxPro fix commit, or discontinue the library if no supported build exists, and restrict network access to affected applications meanwhile.",
  "confidence": "high",
  "provenance": [
    {
      "fields": [
        "cvss",
        "exploitation.attack_complexity",
        "exploitation.exploit_available",
        "references",
        "published_at"
      ],
      "source": "https://nvd.nist.gov/vuln/detail/CVE-2021-23758",
      "retrieved_at": "2026-09-21T07:05:11.841Z",
      "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": "2026-09-21T07:05:11.841Z",
      "confidence": "high",
      "extractor": "scrty-crds-pipeline/0.1"
    },
    {
      "fields": [
        "epss"
      ],
      "source": "https://api.first.org/data/v1/epss?cve=CVE-2021-23758",
      "retrieved_at": "2026-09-21T07:05:11.841Z",
      "confidence": "high",
      "extractor": "scrty-crds-pipeline/0.1"
    },
    {
      "fields": [
        "title",
        "summary",
        "severity",
        "remediation",
        "mitre_attack",
        "kill_chain",
        "recommended_action",
        "confidence",
        "tags",
        "exploitation.prerequisites"
      ],
      "source": "https://nvd.nist.gov/vuln/detail/CVE-2021-23758",
      "retrieved_at": "2026-09-21T07:05:11.841Z",
      "confidence": "high",
      "extractor": "claude-code"
    }
  ],
  "references": [
    {
      "type": "cve",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2021-23758",
      "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://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57"
    },
    {
      "type": "exploit",
      "url": "http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html"
    },
    {
      "type": "exploit",
      "url": "https://blog.talosintelligence.com/uat-10147-chinese-speaking-adversary-integrates-agentic-ai-into-post-compromise-operations/"
    }
  ],
  "published_at": "2021-12-03T20:15:07.557Z",
  "issued_at": "2026-09-21T07:05:11.841Z",
  "tags": [
    "ajaxpro",
    "deserialization",
    "dotnet",
    "web-application"
  ]
}