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Vulnerabilities

Security fix · CVE-2026-118262

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

Published Oct 23, 2026 · catalog updated Oct 28, 2026 · Echo: WebSocket proxy can

Last checked Nov 4, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-118262. EPSS is 0.30%. Act only if a listed version of Echo: WebSocket proxy can is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Echo: WebSocket proxy can).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.30%
Remediation
Advisory link
Affected products
Go github.com/labstack/echo/v4 · Go github.com/labstack/echo/v5

## Impact Echo's Proxy middleware could retain a handler, copy goroutines and network connections after a WebSocket client disconnected if the upstream kept its connection open. The raw proxy waited for both copy directions to finish without reliably closing the other connection when one direction ended. Rejected upgrade responses with HTTP keep-alive were one way to trigger this behavior. Repeated connections can accumulate resources and cause denial of service. The impact depends on the proxy route's accessibility, upstream behavior and configured connection deadlines. This is a medium-severity resource-retention issue; no confidentiality or integrity impact is claimed. ## Affected versions and patch Affected versions are v4.15.0 through v4.16.0 and v5.0.0 through v5.4.0. The regression was introduced by commit e2133320c7, merged in #2852. Upgrade to [v4.16.1](https://github.com/labstack/echo/releases/tag/v4.16.1) or [v5.4.1](https://github.com/labstack/echo/releases/tag/v5.4.1). The patch uses Go's HTTP reverse proxy, preserves ordinary HTTP handling for rejected upgrades, and closes both sides of a WebSocket tunnel when either direction ends. It also covers an upstream that receives client EOF but deliberately keeps its side open. Fix commits: [v4](https://github.com/labstack/echo/commit/3fb0ba7e17645bb65611e2a08875d0a2f65c421f), [v5](https://github.com/labstack/echo/commit/1855061e572ae9dab727c811d8382f266bfbaaec). ## Workarounds Disable WebSocket proxy routes until upgrading, or apply bounded connection lifetimes and resource limits at the frontend and upstream. Server idle timeouts alone may not cover hijacked WebSocket connections. ## Credits Reported by @irisitymichaelgrundberg.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Go github.com/labstack/echo/v44.15.0 → 4.16.1
  • Go github.com/labstack/echo/v55.0.0 → 5.4.1

How to fix CVE-2026-118262

  • Upgrade

    CVE-2026-118262 lists a fix boundary at 4.16.1. Compare the installed build with that boundary before you change production.

  • Version check

    Seen in 4.15.0 → 4.16.1 · 1 other packages on the advisory

  • Advisory

    Open the cve_org record and follow its fix.

  • Official advisories

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-118262. EPSS is 0.30%. Act only if a listed version of Echo: WebSocket proxy can is installed.

Which versions are affected?

Compare what you have installed with 4.15.0 → 4.16.1, 5.0.0 → 5.4.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-772: Missing Release of Resource after Effective Lifetime. EPSS 0.30%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 23, 2026 · Go Vulnerability Database

    Detected

    ## Impact Echo's Proxy middleware could retain a handler, copy goroutines and network connections after a WebSocket client disconnected if the upstream kept its connection open. The raw proxy waited for both copy directions to finish without reliably closing the other connection when one direction ended. Rejected upgrade responses with HTTP keep-alive were one way to trigger this behavior. Repeate

  2. Oct 28, 2026 · Go Vulnerability Database

    Fix available

    github.com/labstack/echo/v4 fixed in 4.16.1; github.com/labstack/echo/v5 fixed in 5.4.1

  3. Oct 28, 2026 · Go Vulnerability Database

    Fix available

    github.com/labstack/echo/v4 fixed in 4.16.1

  4. Oct 28, 2026 · Go Vulnerability Database

    Fix available

    github.com/labstack/echo/v5 fixed in 5.4.1

  5. Oct 28, 2026 · Go Vulnerability Database

    Updated

    ## Impact Echo's Proxy middleware could retain a handler, copy goroutines and network connections after a WebSocket client disconnected if the upstream kept its connection open. The raw proxy waited for both copy directions to finish without reliably closing the other connection when one direction ended. Rejected upgrade responses with HTTP keep-alive were one way to trigger this behavior. Repeate

Sources

References

Freshness

Last verified in this catalog Nov 4, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgOct 29, 2026
  • Go Vulnerability DatabaseOct 29, 2026