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[ CVE-2026-118262 · Published 28 Oct 2026 ]

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

CVSS 8.2 EPSS <1%Fix available

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

  • github.com/labstack/echo/v4 4.16.1Fixed version · GitHub Advisories · go package github.com/labstack/echo/v4: upgrade to 4.16.1 or later (affected >= 4.15.0, < 4.16.1)
  • github.com/labstack/echo/v5 5.4.1Fixed version · GitHub Advisories · go package github.com/labstack/echo/v5: upgrade to 5.4.1 or later (affected >= 5.0.0, < 5.4.1)

[ Packages ]Affected open-source packages

  • github.com/labstack/echo/v4 goAffected >= 4.15.0, < 4.16.1 · fixed in 4.16.1 · GHSA-9969-6676-49h5
  • github.com/labstack/echo/v5 goAffected >= 5.0.0, < 5.4.1 · fixed in 5.4.1 · GHSA-9969-6676-49h5

[ References ]References