Envoy: Segmentation fault when using %REQUESTED_SERVER_NAME% in log format

{
  "id": "ad58d4c5fe0710f4425c6e1d09502f684ee01d87724c1bf9a967d9a48ca59a06",
  "url": "https://osv.dev/vulnerability/CVE-2026-47220",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Envoy: Segmentation fault when using %REQUESTED_SERVER_NAME% in log format",
    "summary": "Envoy is an open source edge and service proxy designed for cloud-native applications. From 1.37.0 until 1.37.5 and 1.38.3, when the %REQUESTED_SERVER_NAME(X:Y)% is used in log format and host related options is specified, like HOST_FIRST, SNI_FIRST, it's possible to crash Envoy when the specified host header is missing in the request headers. This vulnerability is fixed in 1.37.5 and 1.38.3.",
    "evidence": "osv:CVE-2026-47220",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-47220",
      "aliases": [
        "BIT-envoy-2026-47220",
        "CVE-2026-47220",
        "GHSA-j9wh-4qfm-wf2v"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/envoyproxy/envoy",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6d9bb7d9a85d616b220d1f8fe67b61f82bbdb8d3"
                },
                {
                  "fixed": "f97695a50e11f5ff6719e129a466bf9204b64a7f"
                },
                {
                  "introduced": "f1dd21b16c244bda00edfb5ffce577e12d0d2ec2"
                },
                {
                  "fixed": "0ebfcfe5b0484b89ca85b761da9e05ce75dbda8d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.37.0"
                      },
                      {
                        "fixed": "1.37.5"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "1.38.0"
                      },
                      {
                        "fixed": "1.38.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.38.2",
            "v1.37.4",
            "v1.38.1",
            "v1.37.3",
            "v1.38.0",
            "v1.37.2",
            "v1.37.1",
            "v1.37.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47220.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:29.343422416Z",
      "provider": "osv",
      "references": [
        "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47220.json",
        "https://access.redhat.com/security/cve/CVE-2026-47220",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47220.json",
        "https://github.com/envoyproxy/envoy/security/advisories/GHSA-j9wh-4qfm-wf2v",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-47220",
        "https://bugzilla.redhat.com/show_bug.cgi?id=2493652"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-476"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47220.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-47220",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 496334,
  "published_at": "2026-06-26T18:02:17.679+00:00"
}