CVE-2026-118262
Echo: WebSocket proxy can retain connections and handlers after client disconnect
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 and workarounds
Fix
github.com/labstack/echo/v4 (Go): OSV reports a fixed version 4.16.1. Check the advisory for supported release branches.
Source: OSV GHSA-9969-6676-49h5Fix
github.com/labstack/echo/v5 (Go): OSV reports a fixed version 5.4.1. Check the advisory for supported release branches.
Source: OSV GHSA-9969-6676-49h5Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| echo labstack |
>= 4.15.0, < 4.16.1 (affected) >= 5.0.0, < 5.4.1 (affected) |
CNA: GitHub_M |
github.com/labstack/echo/v4github.com/labstack/echo/v4
Go |
≥ 4.15.0; < 4.16.1 (affected, semver); OSV events: introduced 4.15.0; fixed 4.16.1Source events (semver)Other versions: unaffected |
OSV GHSA-9969-6676-49h5 |
github.com/labstack/echo/v5github.com/labstack/echo/v5
Go |
≥ 5.0.0; < 5.4.1 (affected, semver); OSV events: introduced 5.0.0; fixed 5.4.1Source events (semver)Other versions: unaffected |
OSV GHSA-9969-6676-49h5 |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 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 | CNA: GitHub_M |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaecCNA: GitHub_M · x_refsource_MISC
- https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421fCNA: GitHub_M · x_refsource_MISC
- https://github.com/labstack/echo/releases/tag/v4.16.1CNA: GitHub_M · x_refsource_MISC
- https://github.com/labstack/echo/releases/tag/v5.4.1CNA: GitHub_M · x_refsource_MISC
- https://github.com/advisories/GHSA-9969-6676-49h5OSV / GitHub Security Advisories · advisory
- https://osv.dev/vulnerability/GHSA-9969-6676-49h5OSV / GitHub Security Advisories · osv
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