Klever-Go: Unauthenticated WebSocket /subscribe: no read-size limit, no connection cap, permissive origin -> remote node memory/goroutine exhaustion (DoS)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-86065: 0.43% estimated exploitation activity in the next 30 days; percentile 36.84 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The unauthenticated WebSocket endpoint GET /subscribe is registered open: true by default (config/node/api.yaml) and lets a remote, unauthenticated client exhaust the node's memory and goroutines. Because the REST API runs IN-PROCESS with the node — network/api/api.go Start(...) ends with ws.Run(kleverFacade.RestAPIInterface()) — exhausting/killing the API process takes down the entire node, including its P2P and consensus participation. No API key, account, stake, or funds are required. Three compounding, independently-exploitable gaps stack on this one endpoint: 1. Permissive origin — upgrader.CheckOrigin always returns true (network/api/websocket/routes.go), so any web origin can complete the handshake. 2. No read-size limit — the connection never calls conn.SetReadLimit(...). gorilla's default is UNLIMITED, so a single conn.ReadJSON (processSubscription) or conn.ReadMessage (client.loopIn) can be forced to allocate an arbitrarily large buffer from ONE frame. 3. No…

Published by the source

23 Sep 2026, 19:16 UTC

Last modified by the source

1 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4fwh-wrm6-97xm

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6581

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4fwh-wrm6-97xm

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# Patch Next advisory brief: CVE-2026-86065

Advisory: Klever-Go: Unauthenticated WebSocket /subscribe: no read-size limit, no connection cap, permissive origin -> remote node memory/goroutine exhaustion (DoS)
IDs: CVE-2026-86065, GHSA-4fwh-wrm6-97xm
Record: https://patchnext.com/advisories/cve-2026-86065 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/klever-io/klever-go 1.7.20. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/klever-io/klever-go: affected < 1.7.20; fixed in 1.7.20

## Suggested inspection (read-only)
- Go github.com/klever-io/klever-go: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/klever-io/klever-go.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GO-2026-6581 (OSV record GO-2026-6581 lists affected ranges: Go github.com/klever-io/klever-go >=0 <1.7.20 (fixed))
- Verified: https://osv.dev/vulnerability/GHSA-4fwh-wrm6-97xm (OSV record GHSA-4fwh-wrm6-97xm lists affected ranges: Go github.com/klever-io/klever-go >=0 <1.7.20 (fixed))
- Verified: https://github.com/advisories/GHSA-4fwh-wrm6-97xm (GitHub-reviewed advisory GHSA-4fwh-wrm6-97xm lists affected ranges: Go github.com/klever-io/klever-go >=0 <1.7.20)

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