Echo: WebSocket proxy can retain connections and handlers after client disconnect

{
  "id": "6b8e8b1592293a21aa2e979141a2c4440bcb1fc2596f2138bc25d814b61f7959",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-118262",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Echo: WebSocket proxy can retain connections and handlers after client disconnect",
    "summary": "Echo is a Go web framework. From 4.15.0 until 4.16.1 and 5.4.1, Echo's Proxy middleware can retain a handler, copy goroutines, and network connections after a WebSocket client disconnects when the upstream keeps its connection open. The raw proxy waits for both copy directions without reliably closing the peer connection when one direction ends, including when a rejected upgrade response uses HTTP keep-alive. Repeated connections can accumulate resources and cause denial of service, depending on proxy-route accessibility, upstream behavior, and connection deadlines. This issue is fixed in 4.16.1 and 5.4.1.",
    "evidence": "cve:CVE-2026-118262",
    "products": [
      {
        "name": {
          "value": "echo",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-118262",
      "aliases": [
        "CVE-2026-118262"
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "version": "4.0",
            "baseScore": 8.2,
            "attackVector": "NETWORK",
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
            "userInteraction": "NONE",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "privilegesRequired": "NONE",
            "subIntegrityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "subAvailabilityImpact": "NONE",
            "vulnAvailabilityImpact": "HIGH",
            "subConfidentialityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE"
          }
        }
      ],
      "affected": [
        {
          "vendor": "labstack",
          "product": "echo",
          "versions": [
            {
              "status": "affected",
              "version": ">= 4.15.0, < 4.16.1"
            },
            {
              "status": "affected",
              "version": ">= 5.0.0, < 5.4.1"
            }
          ]
        }
      ],
      "modified": "2026-10-28T19:00:12.315Z",
      "provider": "cve",
      "references": [
        "https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5",
        "https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec",
        "https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f",
        "https://github.com/labstack/echo/releases/tag/v4.16.1",
        "https://github.com/labstack/echo/releases/tag/v5.4.1"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
          "shortName": "GitHub_M",
          "dateUpdated": "2026-10-28T19:00:12.315Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-118262",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 477103,
  "published_at": "2026-10-28T19:00:12.315+00:00"
}