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CVE-2019-18802

Status: ModifiedCritical (9.8)—

An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat "header-value " as a different string from "header-value" so for example with the Host header "example.com " one could bypass "example.com" matchers.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Envoyproxy — Envoy

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2019-18802",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 7.5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 6.4,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2019-12-13T13:15:11.383",
  "references": [
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html",
      "source": "cve@mitre.org"
    },
    {
      "url": "https://blog.envoyproxy.io",
      "tags": [
        "Product"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://github.com/envoyproxy/envoy/commits/master",
      "tags": [
        "Patch"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://groups.google.com/forum/#%21forum/envoy-users",
      "source": "cve@mitre.org"
    },
    {
      "url": "http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00034.html",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://blog.envoyproxy.io",
      "tags": [
        "Product"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/envoyproxy/envoy/commits/master",
      "tags": [
        "Patch"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-356m-vhw2-wcm4",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://groups.google.com/forum/#%21forum/envoy-users",
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat \"header-value \" as a different string from \"header-value\" so for example with the Host header \"example.com \" one could bypass \"example.com\" matchers."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema en Envoy versión 1.12.0. Un cliente remoto no confiable puede enviar un encabezado HTTP (como Host) con espacios en blanco después del contenido del encabezado. Envoy tratará el \"header-value \" como una cadena diferente del \"header-value\", de modo que, por ejemplo, con el encabezado Host \"example.com \" se podrían omitir los comparadores de \"example.com\"."
    }
  ],
  "lastModified": "2026-06-17T02:25:21.857",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "A9FE9447-DDAB-42A3-827A-DAB57328D902",
              "versionEndIncluding": "1.12.1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org"
}