CVE-2026-73548

{
  "etk_id": "ETK-2026-772",
  "cve_id": "CVE-2026-73548",
  "display_id": "CVE-2026-73548",
  "ghsa_id": "GHSA-3vhp-c83q-jqc2",
  "euvd_id": "EUVD-2026-84103",
  "status": "published",
  "anchor_state": "anchored",
  "title": "HTTP request smuggling in Envoy upgrade handling",
  "summary": "Envoy can desynchronize requests on shared keep-alive HTTP/1.1 upstream connections when handling HTTP/2 extended CONNECT for configured non-WebSocket upgrades. An unauthenticated client may cause a different downstream client to receive a response intended for another request. Exploitation requires extended CONNECT, a configured non-WebSocket upgrade type, and shared upstream connection pooling.",
  "mitigation": "Upgrade Envoy to 1.39.1, 1.38.4, 1.37.6, 1.36.10 or later.",
  "vendor": "envoy proxy",
  "product": "envoy proxy:Envoy",
  "affected": [
    {
      "affected_notes": [],
      "affected_ranges": [
        "<1.40.0"
      ],
      "ecosystem": "envoy proxy",
      "fixed_versions": [
        "1.39.1",
        "1.38.4",
        "1.37.6",
        "1.36.10"
      ],
      "package_name": "Envoy",
      "purl": null
    }
  ],
  "cwes": null,
  "cvss_score": 7.5,
  "cvss_src": "cna_vendor",
  "cvss_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
  "epss_score": 0.0047,
  "epss_percentile": 0.3895,
  "epss_asof": "2026-10-20",
  "automation": "deterministic",
  "check": true,
  "check_confidence_basis": "differential",
  "exploit": false,
  "pipeline_minutes": 33.29381968333333,
  "t0_at": "2026-09-21T19:35:15.275000+00:00",
  "signals": {
    "check": {
      "at": "2026-10-06T14:23:41.963719+00:00",
      "days": 14.78364223054398,
      "is_lower_bound": false,
      "measured_at": "2026-09-21T19:35:15.275000+00:00",
      "url": null
    },
    "trigger_signal": {
      "at": "2026-09-21T19:35:15.275000+00:00",
      "days": 0,
      "is_lower_bound": false,
      "measured_at": "2026-09-21T19:35:15.275000+00:00",
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2"
    }
  }
}