Vulnerability-Lookup

GHSA-9969-6676-49H5

Vulnerability from github – Published: 2026-10-23 20:50 – Updated: 2026-10-28 19:00

Summary

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

Details

Impact

Echo's Proxy middleware could retain a handler, copy goroutines and network connections after a WebSocket client disconnected if the upstream kept its connection open. The raw proxy waited for both copy directions to finish without reliably closing the other connection when one direction ended. Rejected upgrade responses with HTTP keep-alive were one way to trigger this behavior.

Repeated connections can accumulate resources and cause denial of service. The impact depends on the proxy route's accessibility, upstream behavior and configured connection deadlines. This is a medium-severity resource-retention issue; no confidentiality or integrity impact is claimed.

Affected versions and patch

Affected versions are v4.15.0 through v4.16.0 and v5.0.0 through v5.4.0. The regression was introduced by commit e2133320c7, merged in #2852.

Upgrade to v4.16.1 or v5.4.1. The patch uses Go's HTTP reverse proxy, preserves ordinary HTTP handling for rejected upgrades, and closes both sides of a WebSocket tunnel when either direction ends. It also covers an upstream that receives client EOF but deliberately keeps its side open.

Fix commits: v4, v5.

Workarounds

Disable WebSocket proxy routes until upgrading, or apply bounded connection lifetimes and resource limits at the frontend and upstream. Server idle timeouts alone may not cover hijacked WebSocket connections.

Credits

Reported by @irisitymichaelgrundberg.

Severity

8.2 (High)


                  
                    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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/labstack/echo/v4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.15.0"
            },
            {
              "fixed": "4.16.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/labstack/echo/v5"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0"
            },
            {
              "fixed": "5.4.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-118262"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-772"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-23T20:50:17Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Impact\n\nEcho\u0027s Proxy middleware could retain a handler, copy goroutines and network connections after a WebSocket client disconnected if the upstream kept its connection open. The raw proxy waited for both copy directions to finish without reliably closing the other connection when one direction ended. Rejected upgrade responses with HTTP keep-alive were one way to trigger this behavior.\n\nRepeated connections can accumulate resources and cause denial of service. The impact depends on the proxy route\u0027s accessibility, upstream behavior and configured connection deadlines. This is a medium-severity resource-retention issue; no confidentiality or integrity impact is claimed.\n\n## Affected versions and patch\n\nAffected versions are v4.15.0 through v4.16.0 and v5.0.0 through v5.4.0. The regression was introduced by commit e2133320c7, merged in #2852.\n\nUpgrade to [v4.16.1](https://github.com/labstack/echo/releases/tag/v4.16.1) or [v5.4.1](https://github.com/labstack/echo/releases/tag/v5.4.1). The patch uses Go\u0027s HTTP reverse proxy, preserves ordinary HTTP handling for rejected upgrades, and closes both sides of a WebSocket tunnel when either direction ends. It also covers an upstream that receives client EOF but deliberately keeps its side open.\n\nFix commits: [v4](https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f), [v5](https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec).\n\n## Workarounds\n\nDisable WebSocket proxy routes until upgrading, or apply bounded connection lifetimes and resource limits at the frontend and upstream. Server idle timeouts alone may not cover hijacked WebSocket connections.\n\n## Credits\n\nReported by @irisitymichaelgrundberg.",
  "id": "GHSA-9969-6676-49h5",
  "modified": "2026-10-28T19:00:20Z",
  "published": "2026-10-23T20:50:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec"
    },
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/labstack/echo"
    },
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/releases/tag/v4.16.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/releases/tag/v5.4.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Echo: WebSocket proxy can retain connections and handlers after client disconnect"
}

CVE-2026-118262 (GCVE-0-2026-118262)

Vulnerability from cvelistv5 – Published: 2026-10-28 19:00 – Updated: 2026-10-28 19:00

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.

Severity

8.2 (High)


                        
                          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

CWE

CWE-772 - Missing Release of Resource after Effective Lifetime

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 8129 records in the last 180 days details

References

5 references

URL	Tags
https://github.com/labstack/echo/security/advisor…	x_refsource_CONFIRM
https://github.com/labstack/echo/commit/1855061e5…	x_refsource_MISC
https://github.com/labstack/echo/commit/3fb0ba7e1…	x_refsource_MISC
https://github.com/labstack/echo/releases/tag/v4.16.1	x_refsource_MISC
https://github.com/labstack/echo/releases/tag/v5.4.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
labstack	echo	Affected: >= 4.15.0, < 4.16.1 Affected: >= 5.0.0, < 5.4.1

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JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "echo",
          "vendor": "labstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.15.0, \u003c 4.16.1"
            },
            {
              "status": "affected",
              "version": "\u003e= 5.0.0, \u003c 5.4.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Echo is a Go web framework. From 4.15.0 until 4.16.1 and 5.4.1, Echo\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-772",
              "description": "CWE-772: Missing Release of Resource after Effective Lifetime",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T19:00:12.315Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5"
        },
        {
          "name": "https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec"
        },
        {
          "name": "https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f"
        },
        {
          "name": "https://github.com/labstack/echo/releases/tag/v4.16.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/labstack/echo/releases/tag/v4.16.1"
        },
        {
          "name": "https://github.com/labstack/echo/releases/tag/v5.4.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/labstack/echo/releases/tag/v5.4.1"
        }
      ],
      "source": {
        "advisory": "GHSA-9969-6676-49h5",
        "discovery": "UNKNOWN"
      },
      "title": "Echo: WebSocket proxy can retain connections and handlers after client disconnect"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-118262",
    "datePublished": "2026-10-28T19:00:12.315Z",
    "dateReserved": "2026-10-27T20:13:55.314Z",
    "dateUpdated": "2026-10-28T19:00:12.315Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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