# CVE-2026-86065: Klever-Go unauthenticated WebSocket /subscribe remote DoS

Source: https://junglewise.ai/threats/cve-2026-86065-klever-go-unauthenticated-websocket-subscribe-remote-dos  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-86065 · Severity: high · CVSS 7.5 · Published 2026-09-23

Klever-Go's WebSocket subscription endpoint allows unauthenticated remote attackers to exhaust a node's memory and goroutines, crashing the entire node including its P2P and consensus functions. An attacker can send a single oversized message or open many connections to force resource exhaustion; the endpoint is exposed by default and accepts cross-origin requests, making it reachable even from browser-based attacks. No authentication, account, stake, or funds are required.

Technologies: [github.com/klever-io/klever-go (Go)](https://junglewise.ai/threats/technologies/github-com-klever-io-klever-go). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-86065 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86065 being exploited in the wild.

**How severe is CVE-2026-86065?** High severity, with a CVSS score of 7.5, published 23 September 2026.

**Which products and versions are affected?** github.com/klever-io/klever-go (Go) < 1.7.20, SEMVER:introduced=0,fixed=1.7.20.

**Is there a fix for CVE-2026-86065?** Yes. github.com/klever-io/klever-go (Go): upgrade to 1.7.20 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86065 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-86065?** Check whether you run github.com/klever-io/klever-go (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/klever-io/klever-go (Go): upgrade to 1.7.20 or later

  ```sh
  go get github.com/klever-io/klever-go@v1.7.20
  ```


## Technical details

The unauthenticated GET /subscribe WebSocket endpoint (network/api/websocket/routes.go) contains three compounding remote code execution gaps: (1) CheckOrigin always returns true, permitting cross-origin WebSocket upgrades; (2) no conn.SetReadLimit() is enforced, allowing a single WebSocket frame to trigger unbounded heap allocation in gorilla's JSON parsing; (3) no per-connection, per-IP, or global cap on live WebSocket connections, and req.Addresses is uncapped, causing both goroutine exhaustion and hub-map memory growth. The REST API runs in-process with the node, so crashing the API kills P2P and consensus participation. Attack vectors include network-reachable APIs and cross-origin browser drive-by attacks against localhost-bound nodes. Three independent PoCs confirm all gaps in production code at commit 23b74e1.

## Affected products

- Klever Klever-Go up to commit 23b74e1

## Identifiers

- CVE-2026-86065
- GHSA-4fwh-wrm6-97xm
- GO-2026-6581

## Timeline

- 2026-09-23: disclosed: GitHub advisory GHSA-4fwh-wrm6-97xm published

## Related threats

- [Klever-Go /log endpoint unauthenticated logging configuration manipulation](https://junglewise.ai/threats/cve-2026-86064-klever-go-log-endpoint-unauthenticated-logging-configuration)
- [Klever-Go Elasticsearch injection via account name](https://junglewise.ai/threats/cve-2026-82409-klever-go-elasticsearch-injection-via-account-name)
- [Klever-Go BLS public key validation bypass in validator registration](https://junglewise.ai/threats/cve-2026-82407-klever-go-bls-public-key-validation-bypass-in-validator)
- [Klever-Go marketplace Buy missing IsClaimed guard](https://junglewise.ai/threats/cve-2026-82406-klever-go-marketplace-buy-missing-isclaimed-guard)
- [Klever-Go account takeover via authorization bypass in UpdateAccountPermission](https://junglewise.ai/threats/cve-2026-82405-klever-go-account-takeover-via-authorization-bypass-in)