GHSA-9969-6676-49h5

Source

https://github.com/advisories/GHSA-9969-6676-49h5

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9969-6676-49h5/GHSA-9969-6676-49h5.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-9969-6676-49h5

Published

2026-10-23T20:50:17Z

Modified

2026-10-23T21:00:05Z

Severity

8.2 (High) CVSS_V4 - 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 CVSS Calculator

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.

Database specific

{
    "cwe_ids":  [
        "CWE-772"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-10-23T20:50:17Z",
    "nvd_published_at":  null,
    "severity":  "HIGH"
}

References

Affected packages

Go / github.com/labstack/echo/v4

Package

Name: github.com/labstack/echo/v4; View open source insights on deps.dev
Purl: pkg:golang/github.com/labstack/echo/v4

Affected ranges

Type: SEMVER
Events: Introduced

4.15.0

Fixed

4.16.1

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9969-6676-49h5/GHSA-9969-6676-49h5.json"

Go / github.com/labstack/echo/v5

Package

Name: github.com/labstack/echo/v5; View open source insights on deps.dev
Purl: pkg:golang/github.com/labstack/echo/v5

Affected ranges

Type: SEMVER
Events: Introduced

5.0.0

Fixed

5.4.1

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-9969-6676-49h5/GHSA-9969-6676-49h5.json"