What’s Vulnerable › Vulnerabilities

CVE-2026-118262: Echo: WebSocket proxy can retain connections and handlers after client disconnect

• Severity: high (CVSS 8.2 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-28 · updated 2026-10-29
• Weakness: CWE-772

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.

Affected products

• labstack echo: from 4.15.0, < 4.16.1; from 5.0.0, < 5.4.1

References

• https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec
• https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f
• https://github.com/labstack/echo/releases/tag/v4.16.1
• https://github.com/labstack/echo/releases/tag/v5.4.1
• https://github.com/labstack/echo/security/advisories/GHSA-9969-6676-49h5

Get alerted when CVE-2026-118262 or the next vulnerability affects your stack