CVE-2026-73550

Description

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 7.5 / 10
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Effective score: 7.5 / 10 HIGH source: CNA overview
CWE(s): CWE-401
Reserved: 2026-08-12
Published: 2026-09-21 19:49 UTC
Last updated: 2026-09-21 19:49 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/73xxx/CVE-2026-73550.json
Linked Threat: CVE-2026-73550 — Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-21 20:17:28 UTC
NVD last modified: 2026-09-21 20:17:28 UTC
NVD CVSS v3.1: 7.5 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploitability subscore: 3.9 / 10
Impact subscore: 3.6 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84111
Assigner: GitHub_M
Published: Sep 21, 2026, 7:49:28 PM
Updated: Sep 21, 2026, 7:49:28 PM
EUVD base score (CVSS 3.1): 7.5 / 10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EUVD-reported EPSS: 0.0000
Vendors: envoyproxy
Products: envoy (1.37.0, < 1.37.6)

envoy (< 1.36.10)

envoy (1.38.0, < 1.38.4)

envoy (1.39.0, < 1.39.1)

ENISA description: 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.

EUVD references (9)

Affected products (1)

Vendor	Product	Versions	Platforms
envoyproxy	envoy	`< 1.36.10` (affected), `>= 1.37.0, < 1.37.6` (affected), `>= 1.38.0, < 1.38.4` (affected), `>= 1.39.0, < 1.39.1` (affected)	—

Vendor references (9)

References embedded in the original CVE record by the assigning CNA.

https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh x_refsource_CONFIRM
https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80 x_refsource_MISC
https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2 x_refsource_MISC
https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300 x_refsource_MISC
https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b x_refsource_MISC
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10 x_refsource_MISC
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6 x_refsource_MISC
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4 x_refsource_MISC
https://github.com/envoyproxy/envoy/releases/tag/v1.39.1 x_refsource_MISC

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (9)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80 security-advisories@github.com
https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2 security-advisories@github.com
https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300 security-advisories@github.com
https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b security-advisories@github.com
https://github.com/envoyproxy/envoy/releases/tag/v1.36.10 security-advisories@github.com
https://github.com/envoyproxy/envoy/releases/tag/v1.37.6 security-advisories@github.com
https://github.com/envoyproxy/envoy/releases/tag/v1.38.4 security-advisories@github.com
https://github.com/envoyproxy/envoy/releases/tag/v1.39.1 security-advisories@github.com
https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh security-advisories@github.com

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

July 2026 Critical Patch Update Released | security - Oracle Blogs

web:blogs.oracle.com

For more information about the Critical Patch Update program, see the security vulnerability remediation practices page located on the Oracle Trust Center.

2026-09-22 16:47 UTC
Microsoft Update Catalog

web:catalog.update.microsoft.com

Welcome to the Microsoft Update Catalog site. We want your feedback! Visit our newsgroup or send us an email to provide us with your thoughts and suggestions. To get started using the site, enter in your search terms in the Search box above or visit our FAQ for search tips. |Newsgroup|Send us your feedback

2026-09-22 16:47 UTC
Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-22 16:47 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-22 16:47 UTC
SAP Security Patch Day - June 2026

web:support.sap.com

SAP security Patch Day Bulletin This post shares the information on security notes that remediate vulnerabilities discovered in SAP products. SAP strongly recommends that the customer visits the support portal and applies patches on priority to protect their SAP landscape. On 9th of June 2026 , SAP security patch day saw the release of 15 new security notes.

2026-09-22 16:47 UTC
What Is CVE Remediation in 2026? - aikido.dev

web:www.aikido.dev

None of these is a clean fix , which is why the decision on how to remediate depends on knowing what package versions are running in production and why. This post will cover how AI has accelerated CVE detection and discovery, the upgrade trap, what CVE remediation actually involves in 2026 , and how to solve the CVE remediation problem.

2026-09-22 16:47 UTC
Oracle's first monthly patch release fixes 35 flaws, including 11 rated ...

web:www.csoonline.com

Oracle has released the first security fixes in its new monthly Critical Security Patch Update (CSPU) cycle, designed to address urgent vulnerabilities that can't wait for the company's ...

2026-09-22 16:47 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-22 16:47 UTC
Oracle Critical Security Patch Update Advisory - June 2026

web:www.oracle.com

Additional CVEs addressed are: The patch for CVE - 2026 -34481 also addresses CVE - 2026 -34477, CVE - 2026 -34478, CVE - 2026 -34479, and CVE - 2026 -34480. Oracle Fusion Middleware Risk Matrix This Critical Security Patch Update contains 106 new security patches for Oracle Fusion Middleware. 53 of these vulnerabilities may be remotely exploitable without authentication, i.e., may be exploited over a ...

2026-09-22 16:47 UTC
CVE-2026-73550: envoyproxy envoy: Envoy is an open source edge ... - Rapid7

web:www.rapid7.com

CVE-2026-73550 : envoyproxy envoy: Envoy is an open source edge and service proxy designed for cloud-native applications. View severity, references, and remediation details from Rapid7.

2026-09-22 16:47 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-73550.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "< 1.36.10"
            },
            {
              "status": "affected",
              "version": ">= 1.37.0, < 1.37.6"
            },
            {
              "status": "affected",
              "version": ">= 1.38.0, < 1.38.4"
            },
            {
              "status": "affected",
              "version": ">= 1.39.0, < 1.39.1"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-401",
              "description": "CWE-401: Missing Release of Memory after Effective Lifetime",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-21T19:49:28.641Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-qgf6-qvhw-4hvh"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/commit/0910997f70e91d2d20c329bb507bfce44ce01f80"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2",
          "tags": [
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          ],
          "url": "https://github.com/envoyproxy/envoy/commit/1fec994c868df008cdd4ae285aab58a196fd31f2"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/commit/3fd0ffee7ac87adf3bc6e421656bb96310512300"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/commit/fc75d8e35b0d11acbae18b63a0bd96e32e84f61b"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.36.10"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.37.6"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.38.4"
        },
        {
          "name": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/envoyproxy/envoy/releases/tag/v1.39.1"
        }
      ],
      "source": {
        "advisory": "GHSA-qgf6-qvhw-4hvh",
        "discovery": "UNKNOWN"
      },
      "title": "Envoy: HTTP/2 Discarded Host Header 200 GB Header-Copy OOM in Envoy"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73550",
    "datePublished": "2026-09-21T19:49:28.641Z",
    "dateReserved": "2026-08-12T20:53:46.379Z",
    "dateUpdated": "2026-09-21T19:49:28.641Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}