CVE-2026-16123: GoClaw Auth Bypass Vulnerability

CVE-2026-16123 Overview

CVE-2026-16123 is a missing authorization vulnerability [CWE-862] in nextlevelbuilder GoClaw versions up to 3.13.2. The flaw resides in the ToolsInvokeHandler.ServeHTTP function within internal/http/tools_invoke.go, which implements the Invoke Endpoint component. Attackers can reach the endpoint remotely over the network and invoke tool operations without the authorization checks the application should enforce. A public exploit has been referenced, increasing the likelihood of opportunistic abuse against exposed instances.

Critical Impact
Remote attackers with low privileges can bypass authorization on the GoClaw Invoke Endpoint to trigger tool invocations, affecting confidentiality, integrity, and availability of the service.

Affected Products

nextlevelbuilder GoClaw versions up to and including 3.13.2
Component: Invoke Endpoint (internal/http/tools_invoke.go)
Affected function: ToolsInvokeHandler.ServeHTTP

Discovery Timeline

2026-07-18 - CVE-2026-16123 published to the National Vulnerability Database (NVD)
2026-07-22 - Last updated in NVD database

Technical Details for CVE-2026-16123

Vulnerability Analysis

GoClaw exposes an HTTP endpoint that dispatches tool invocation requests through the ToolsInvokeHandler.ServeHTTP handler. The handler processes inbound requests without correctly validating that the caller is authorized to invoke the target tool. Because the authorization decision is missing, any authenticated user with minimal privileges can reach functionality intended for privileged principals.

The issue is classified under [CWE-862] Missing Authorization. The vulnerability results in limited confidentiality, integrity, and availability impact per the CVSS 4.0 vector, but the network attack surface and public exploit availability increase practical exposure. EPSS currently estimates the exploit likelihood at 0.209% with a percentile of 11.239.

Root Cause

The root cause is an omitted authorization check inside ToolsInvokeHandler.ServeHTTP. The handler proceeds to execute tool operations based on request parameters without verifying that the caller's identity or role permits the requested action. Authentication alone is treated as sufficient, so any low-privileged session can trigger sensitive tool logic.

Attack Vector

An attacker sends a crafted HTTP request to the Invoke Endpoint from a network-reachable position. With valid low-privilege credentials, the request bypasses the missing authorization layer and invokes tool handlers directly. No user interaction is required, and exploitation complexity is low. Refer to the GitHub Issue #1217 and VulDB CVE-2026-16123 entries for technical details.

No verified proof-of-concept code is published in a form suitable for reproduction here. Review the GoClaw repository for source-level context on the vulnerable handler.

Detection Methods for CVE-2026-16123

Indicators of Compromise

Unexpected HTTP requests to the GoClaw Invoke Endpoint originating from low-privileged or unusual accounts.
Tool invocation events in application logs that lack a corresponding authorization decision entry.
Spikes in ToolsInvokeHandler activity from a single source address or session token.

Detection Strategies

Instrument ToolsInvokeHandler.ServeHTTP with structured logging that records caller identity, requested tool, and authorization outcome for every request.
Compare invocation logs against a known authorization matrix to flag calls where the caller lacked required permissions.
Alert on repeated 200-response tool invocations from principals who normally have read-only or restricted roles.

Monitoring Recommendations

Forward GoClaw HTTP access and application logs to a centralized log platform for correlation with identity events.
Track baseline invocation patterns per user and role, then alert on statistically anomalous deviations.
Monitor egress traffic and downstream systems affected by tool invocations for signs of unauthorized state changes.

How to Mitigate CVE-2026-16123

Immediate Actions Required

Inventory all GoClaw deployments and identify instances running version 3.13.2 or earlier.
Restrict network access to the Invoke Endpoint using firewall or ingress controls until an upstream fix is applied.
Rotate credentials and review recent invocation logs for evidence of unauthorized tool execution.

Patch Information

At the time of publication, the NVD entry for CVE-2026-16123 does not list a fixed version. Monitor the GoClaw GitHub repository and the linked issue #1217 for maintainer updates and upgrade to any release that explicitly adds authorization checks to ToolsInvokeHandler.ServeHTTP.

Workarounds

Place GoClaw behind a reverse proxy that enforces authorization for the Invoke Endpoint path based on user role or token claims.
Disable or remove the Invoke Endpoint route in configurations where tool invocation is not required.
Limit issuance of GoClaw credentials to trusted users and apply short-lived tokens to reduce the window of exposure.

bash

# Example reverse proxy rule (nginx) restricting the Invoke Endpoint to an internal admin subnet
location /tools/invoke {
    allow 10.10.0.0/24;
    deny all;
    proxy_pass http://goclaw_backend;
}