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CVE-2021-32778

Estado: ModificadaAlta (7.5)—

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions envoy’s procedure for resetting a HTTP/2 stream has O(N^2) complexity, leading to high CPU utilization when a large number of streams are reset. Deployments are susceptible to Denial of Service when Envoy is configured with high limit on H/2 concurrent streams. An attacker wishing to exploit this vulnerability would require a client opening and closing a large number of H/2 streams. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to reduce time complexity of resetting HTTP/2 streams. As a workaround users may limit the number of simultaneous HTTP/2 dreams for upstream and downstream peers to a low number, i.e. 100.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Envoyproxy — Envoy

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2021-32778",
  "cveTags": [],
  "metrics": {
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:N/I:N/A:P",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 5.8,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "LOW",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 3.9
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "envoyproxy",
          "product": "envoy",
          "versions": [
            {
              "status": "affected",
              "version": ">= 1.19.0, < 1.19.1"
            },
            {
              "status": "affected",
              "version": ">= 1.18.0, < 1.18.4"
            },
            {
              "status": "affected",
              "version": ">= 1.17.0, < 1.17.4"
            },
            {
              "status": "affected",
              "version": ">= 1.16.0, < 1.16.5"
            }
          ]
        }
      ]
    }
  ],
  "published": "2021-08-24T21:15:09.553",
  "references": [
    {
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3xh3-33v5-chcc",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history",
      "tags": [
        "Release Notes",
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-834"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-834"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions envoy’s procedure for resetting a HTTP/2 stream has O(N^2) complexity, leading to high CPU utilization when a large number of streams are reset. Deployments are susceptible to Denial of Service when Envoy is configured with high limit on H/2 concurrent streams. An attacker wishing to exploit this vulnerability would require a client opening and closing a large number of H/2 streams. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to reduce time complexity of resetting HTTP/2 streams. As a workaround users may limit the number of simultaneous HTTP/2 dreams for upstream and downstream peers to a low number, i.e. 100."
    },
    {
      "lang": "es",
      "value": "Envoy es un proxy L7 de código abierto y un bus de comunicación diseñado para grandes arquitecturas modernas orientadas a servicios. En las versiones afectadas, el procedimiento de Envoy para restablecer un flujo HTTP/2 presenta una complejidad O(N^2), conllevando a un alto uso de la CPU cuando se restablece un gran número de flujos. Los despliegues son susceptibles a una Denegación de Servicio cuando Envoy está configurado con un alto límite de flujos concurrentes H/2. Un atacante que desee explotar esta vulnerabilidad necesitaría un cliente que abriera y cerrara un gran número de flujos H/2. Envoy  versiones 1.19.1, 1.18.4, 1.17.4 y 1.16.5, contienen correcciones para reducir la complejidad del tiempo de restablecimiento de los flujos HTTP/2. Como solución, los usuarios pueden limitar el número de sueños HTTP/2 simultáneos para los pares ascendentes y descendentes a un número bajo, es decir, 100."
    }
  ],
  "lastModified": "2026-06-17T03:53:36.730",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "AFC3BF7F-5B28-4765-8C6F-E2437A4B425D",
              "versionEndExcluding": "1.16.5",
              "versionStartIncluding": "1.16.0"
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "83547329-1394-417F-93DB-70C1A9D173B0",
              "versionEndExcluding": "1.17.4",
              "versionStartIncluding": "1.17.0"
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "D7376E28-9915-4CA1-A5DB-40874D10E781",
              "versionEndExcluding": "1.18.4",
              "versionStartIncluding": "1.18.0"
            },
            {
              "criteria": "cpe:2.3:a:envoyproxy:envoy:1.19.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "1968AA35-60E2-4A00-84A0-617738B55D33"
            }
          ],
          "operator": "OR"
        }
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  ],
  "sourceIdentifier": "security-advisories@github.com"
}