CVE-2026-118262

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CVE-2026-118262

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

Details: 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.

References: https://github.com/labstack/echo/releases/tag/v4.16.1, https://github.com/labstack/echo/releases/tag/v5.4.1, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/118xxx/CVE-2026-118262.json, https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5, https://nvd.nist.gov/vuln/detail/CVE-2026-118262, https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec, https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f