{
  "id": "CVE-2021-40438",
  "url": "https://spydr.io/cve/CVE-2021-40438",
  "published": "2021-09-16T15:15:07.633Z",
  "modified": "2026-08-06T05:16:35.670Z",
  "score": 9,
  "severity": "critical",
  "cvss_version": "3.1",
  "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H",
  "score_source": "NVD",
  "epss": 0.99999,
  "epss_percentile": 0.99997,
  "exploited": true,
  "kev": {
    "added": "2021-12-01",
    "due": "2021-12-15",
    "action": "Apply updates per vendor instructions.",
    "ransomware": "Known",
    "name": "Apache HTTP Server-Side Request Forgery (SSRF)",
    "notes": "https://nvd.nist.gov/vuln/detail/CVE-2021-40438"
  },
  "ssvc_exploitation": "active",
  "vendors": [
    "Apache Software Foundation"
  ],
  "products": [
    "Apache Software Foundation Apache HTTP Server"
  ],
  "cwes": [
    "CWE-918"
  ],
  "description": "A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user. This issue affects Apache HTTP Server 2.4.48 and earlier.",
  "status": "Analyzed",
  "score_type": "Primary",
  "scores": {
    "cvss_v40": null,
    "cvss_v31": 9,
    "cvss_v30": null
  },
  "references": [
    {
      "url": "https://cert-portal.siemens.com/productcert/pdf/ssa-685781.pdf",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://httpd.apache.org/security/vulnerabilities_24.html",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r210807d0bb55f4aa6fbe1512be6bcc4dacd64e84940429fba329967a%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r2eb200ac1340f69aa22af61ab34780c531d110437910cb9c0ece3b37%40%3Cbugs.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r3925e167d5eb1c75def3750c155d753064e1d34a143028bb32910432%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r61fdbfc26ab170f4e6492ef3bd5197c20b862ce156e9d5a54d4b899c%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r82838efc5fa6fc4c73986399c9b71573589f78b31846aff5bd9b1697%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/r82c077663f9759c7df5a6656f925b3ee4f55fcd33c889ba7cd687029%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.apache.org/thread.html/rf6954e60b1c8e480678ce3d02f61b8a788997785652e9557a3265c00%40%3Cusers.httpd.apache.org%3E",
      "tags": [
        "Mailing List"
      ]
    },
    {
      "url": "https://lists.debian.org/debian-lts-announce/2021/10/msg00001.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SPBR6WUYBJNACHKE65SPL7TJOHX7RHWD/",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNCYSR3BXT36FFF4XTCPL3HDQK4VP45R/",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://security.gentoo.org/glsa/202208-20",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://security.netapp.com/advisory/ntap-20211008-0004/",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-httpd-2.4.49-VWL69sWQ",
      "tags": [
        "Broken Link",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.debian.org/security/2021/dsa-4982",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.oracle.com/security-alerts/cpuapr2022.html",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.oracle.com/security-alerts/cpujan2022.html",
      "tags": [
        "Patch",
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.tenable.com/security/tns-2021-17",
      "tags": [
        "Third Party Advisory"
      ]
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40438",
      "tags": [
        "US Government Resource"
      ]
    }
  ],
  "nvd_url": "https://nvd.nist.gov/vuln/detail/CVE-2021-40438",
  "covered_in": [],
  "attribution": [
    {
      "source": "NVD",
      "url": "https://nvd.nist.gov",
      "notice": "This product uses data from the NVD API but is not endorsed or certified by the NVD."
    },
    {
      "source": "CISA KEV",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "notice": "Known exploited vulnerabilities from the CISA KEV catalog."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss",
      "notice": "Exploit prediction scores from FIRST EPSS."
    }
  ]
}