GHSA-9969-6676-49h5: github.com/labstack/echo/v4 (CVE-2026-118262)

Package	Ecosystem	Affected	Fixed in
github.com/labstack/echo/v4	Go	>=4.15.0, <4.16.1	4.16.1
github.com/labstack/echo/v5	Go	>=5.0.0, <5.4.1	5.4.1

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Echo's Proxy middleware in github.com/labstack/echo/v4 (4.15.0 through 4.16.0) and github.com/labstack/echo/v5 (5.0.0 through 5.4.0) can keep handlers, goroutines and network connections alive after a WebSocket client disconnects, if the upstream keeps its side open. An attacker who can reach a WebSocket proxy route can repeat connections to accumulate resources and cause a denial of service. Upgrade to v4.16.1 or v5.4.1. Until then, disable WebSocket proxy routes or apply bounded connection lifetimes and resource limits.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.2	High	4.0	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	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0030, the 23rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

28 Oct 2026, 19:00 UTC Confirmed by the CVE List
28 Oct 2026, 19:17 UTC Confirmed by NVD
31 Oct 2026, 14:11 UTC First seen by agentprime
31 Oct 2026, 14:11 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.