FKIE_CVE-2026-73550

Vulnerability from fkie_nvd - Published: 2026-09-21 20:17 - Updated: 2026-09-21 20:17
Severity
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy copies every decoded HTTP/2 Host header value before discarding it when :authority is already present. The discarded value bypasses saveHeader, so its bytes and count are not charged against request header limits. An unauthenticated client can use HPACK indexing to submit many references to a large Host value across a bounded number of streams, forcing extreme header-copy allocation and causing the proxy to be out-of-memory killed. The relevant scope boundary is that the demonstrated amplification uses HTTP/2 HPACK and the duplicate Host discard behavior. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.
References
security-advisories@github.comhttps://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80
security-advisories@github.comhttps://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2
security-advisories@github.comhttps://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300
security-advisories@github.comhttps://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b
security-advisories@github.comhttps://github.com/envoyproxy/envoy/releases/tag/v1.36.10
security-advisories@github.comhttps://github.com/envoyproxy/envoy/releases/tag/v1.37.6
security-advisories@github.comhttps://github.com/envoyproxy/envoy/releases/tag/v1.38.4
security-advisories@github.comhttps://github.com/envoyproxy/envoy/releases/tag/v1.39.1
security-advisories@github.comhttps://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.36.10"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.37.0, \u003c 1.37.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.38.0, \u003c 1.38.4"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.39.0, \u003c 1.39.1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy copies every decoded HTTP/2 Host header value before discarding it when :authority is already present. The discarded value bypasses saveHeader, so its bytes and count are not charged against request header limits. An unauthenticated client can use HPACK indexing to submit many references to a large Host value across a bounded number of streams, forcing extreme header-copy allocation and causing the proxy to be out-of-memory killed. The relevant scope boundary is that the demonstrated amplification uses HTTP/2 HPACK and the duplicate Host discard behavior. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1."
    }
  ],
  "id": "CVE-2026-73550",
  "lastModified": "2026-09-21T20:17:28.733",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-21T20:17:28.733",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Primary"
    }
  ]
}



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