Vulnerability-Lookup

GHSA-CXF3-9H37-7RR8

Vulnerability from github – Published: 2026-10-23 20:49 – Updated: 2026-10-28 19:21

Summary

Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls

Details

Impact

Echo's Proxy middleware selected a raw tunnel when the client requested a WebSocket upgrade, before validating whether the configured upstream accepted it. If the upstream returned an ordinary HTTP response and kept the connection alive, subsequent HTTP requests on that connection were forwarded directly to the same upstream without passing through Echo's router or route-specific middleware.

This can bypass authentication or authorization enforced only at Echo's routes. Exploitation requires an accessible proxy route, an upstream that rejects the upgrade without closing the connection, and a target resource on that upstream without independent authorization. The issue does not provide arbitrary-host proxying or bypass the upstream's own authentication.

Affected versions and patch

The raw proxy implementation is present throughout the v4 and v5 release lines up to v4.16.0 and v5.4.0. Runtime reproductions confirmed v4.15.0, v4.16.0, v5.0.0 and v5.4.0; source history also shows the missing upgrade-response validation in v4.0.0.

Upgrade to v4.16.1 or v5.4.1. The patch routes WebSocket upgrades through Go's HTTP reverse proxy and enters a tunnel only after a valid upstream upgrade response. Rejected upgrades remain ordinary HTTP requests.

Fix commits: v4, v5.

Workarounds

Reject WebSocket upgrade requests before they reach affected Echo proxy routes, or enforce authorization independently at every upstream resource. Merely returning a non-101 response from the upstream does not prevent the vulnerable raw tunnel.

Credits

Reported by @Duodum.

Severity

9.1 (Critical)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/labstack/echo/v4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "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-2026-118264"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-444",
      "CWE-863"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-23T20:49:37Z",
    "nvd_published_at": null,
    "severity": "CRITICAL"
  },
  "details": "## Impact\n\nEcho\u0027s Proxy middleware selected a raw tunnel when the client requested a WebSocket upgrade, before validating whether the configured upstream accepted it. If the upstream returned an ordinary HTTP response and kept the connection alive, subsequent HTTP requests on that connection were forwarded directly to the same upstream without passing through Echo\u0027s router or route-specific middleware.\n\nThis can bypass authentication or authorization enforced only at Echo\u0027s routes. Exploitation requires an accessible proxy route, an upstream that rejects the upgrade without closing the connection, and a target resource on that upstream without independent authorization. The issue does not provide arbitrary-host proxying or bypass the upstream\u0027s own authentication.\n\n## Affected versions and patch\n\nThe raw proxy implementation is present throughout the v4 and v5 release lines up to v4.16.0 and v5.4.0. Runtime reproductions confirmed v4.15.0, v4.16.0, v5.0.0 and v5.4.0; source history also shows the missing upgrade-response validation in v4.0.0.\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 routes WebSocket upgrades through Go\u0027s HTTP reverse proxy and enters a tunnel only after a valid upstream upgrade response. Rejected upgrades remain ordinary HTTP requests.\n\nFix commits: [v4](https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f), [v5](https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec).\n\n## Workarounds\n\nReject WebSocket upgrade requests before they reach affected Echo proxy routes, or enforce authorization independently at every upstream resource. Merely returning a non-101 response from the upstream does not prevent the vulnerable raw tunnel.\n\n## Credits\n\nReported by @Duodum.",
  "id": "GHSA-cxf3-9h37-7rr8",
  "modified": "2026-10-28T19:21:31Z",
  "published": "2026-10-23T20:49:37Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/labstack/echo/security/advisories/GHSA-cxf3-9h37-7rr8"
    },
    {
      "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:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls"
}

CVE-2026-118264 (GCVE-0-2026-118264)

Vulnerability from cvelistv5 – Published: 2026-10-28 19:03 – Updated: 2026-10-30 19:21

Title

Echo: Rejected WebSocket upgrades can bypass Echo route-level access controls

Summary

Echo is a Go web framework. From 4.0.0 until 4.16.1 and 5.4.1, Echo's Proxy middleware selects a raw tunnel from a client WebSocket upgrade request before verifying that the configured upstream accepted the upgrade. If the upstream rejects the upgrade with an ordinary keep-alive response, later HTTP requests on the connection are sent directly to that upstream without passing through Echo's router or route-specific middleware. This can bypass authentication or authorization enforced only by Echo routes, but requires an accessible proxy route, a cooperating rejected-upgrade response, and a target without independent upstream authorization. This issue is fixed in 4.16.1 and 5.4.1.

Severity

9.1 (Critical)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-30 19:20 UTC

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
CWE-863 - Incorrect Authorization

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: >= 4.0.0, < 4.16.1 Affected: >= 5.0.0, < 5.4.1

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JSON

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{
  "containers": {
    "adp": [
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        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-118264",
                "options": [
                  {
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                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-30T19:20:57.948930Z",
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      }
    ],
    "cna": {
      "affected": [
        {
          "product": "echo",
          "vendor": "labstack",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.16.1"
            },
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            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Echo is a Go web framework. From 4.0.0 until 4.16.1 and 5.4.1, Echo\u0027s Proxy middleware selects a raw tunnel from a client WebSocket upgrade request before verifying that the configured upstream accepted the upgrade. If the upstream rejects the upgrade with an ordinary keep-alive response, later HTTP requests on the connection are sent directly to that upstream without passing through Echo\u0027s router or route-specific middleware. This can bypass authentication or authorization enforced only by Echo routes, but requires an accessible proxy route, a cooperating rejected-upgrade response, and a target without independent upstream authorization. This issue is fixed in 4.16.1 and 5.4.1."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 9.1,
            "baseSeverity": "CRITICAL",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
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            "version": "4.0",
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      "problemTypes": [
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          "descriptions": [
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          ]
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  },
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}

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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