CVE-2026-31998: Openclaw Authorization Bypass Vulnerability

CVE-2026-31998 Overview

OpenClaw versions 2026.2.22 and 2026.2.23 contain an authorization bypass vulnerability (CWE-863) in the synology-chat channel plugin. When dmPolicy is set to allowlist with an empty allowedUserIds array, the authorization check fails open rather than failing closed. This allows attackers with Synology sender access to bypass authorization checks and trigger unauthorized agent dispatch and downstream tool actions.

Critical Impact

Attackers can bypass intended access controls to execute unauthorized agent operations and downstream tool actions, potentially compromising system integrity and data confidentiality.

Affected Products

• OpenClaw 2026.2.22
• OpenClaw 2026.2.23
• OpenClaw for Node.js (affected versions)

Discovery Timeline

• 2026-03-19 - CVE CVE-2026-31998 published to NVD
• 2026-03-19 - Last updated in NVD database

Technical Details for CVE-2026-31998

Vulnerability Analysis

This authorization bypass vulnerability exists in the synology-chat channel plugin's user allowlist implementation. The core issue lies in the checkUserAllowed() function within extensions/synology-chat/src/security.ts, which was designed to verify whether a user ID exists in an allowed list. The vulnerable implementation treated an empty allowedUserIds array as a permissive state, allowing all users through rather than blocking all users as would be expected from a fail-closed security design.

When administrators configure dmPolicy to allowlist mode intending to restrict access to specific users, but fail to populate the allowedUserIds array (or it becomes empty through misconfiguration), the vulnerable code would grant access to any authenticated Synology sender. This represents a classic fail-open authorization flaw where the absence of explicit allow entries results in implicit universal access.

Root Cause

The root cause is an improper authorization check in the checkUserAllowed() function. The original implementation contained logic that returned true (allow access) when the allowedUserIds array was empty, based on the flawed assumption that an empty allowlist should permit all users. This violates the principle of least privilege and fail-closed security design patterns. The correct behavior for an allowlist with no entries should be to deny all access, forcing administrators to explicitly add authorized users.

Attack Vector

An attacker with access to send messages through the Synology Chat integration can exploit this vulnerability by targeting OpenClaw instances where administrators have configured dmPolicy="allowlist" but left the allowedUserIds array empty. The attack is network-based and requires no user interaction. Upon successful exploitation, the attacker can:

1. Send unauthorized messages to the OpenClaw bot
2. Trigger agent dispatch operations intended only for authorized users
3. Execute downstream tool actions that could modify data, access sensitive information, or perform other privileged operations

// VULNERABLE CODE - From extensions/synology-chat/src/security.ts
/**
 * Check if a user ID is in the allowed list.
 * Empty allowlist = allow all users.  // INCORRECT ASSUMPTION
 */
export function checkUserAllowed(userId: string, allowedUserIds: string[]): boolean {
  if (allowedUserIds.length === 0) return true;  // VULNERABILITY: Fails open
  return allowedUserIds.includes(userId);
}

Source: GitHub Commit Update

Detection Methods for CVE-2026-31998

Indicators of Compromise

• Unexpected agent dispatch events from users not in any configured allowlist
• Anomalous message activity from the synology-chat integration with user IDs that should be blocked
• Tool execution logs showing actions triggered by unauthorized Synology Chat senders
• Audit logs indicating successful access to bot functionality from users outside the expected allowlist

Detection Strategies

• Review OpenClaw configuration files for instances where dmPolicy="allowlist" is set with empty or undefined allowedUserIds arrays
• Monitor agent dispatch logs for actions triggered by users not explicitly authorized in the system
• Implement alerting on synology-chat plugin activity from user IDs that have never been added to an allowlist
• Audit application logs for patterns indicating bypass of access controls in the chat integration

Monitoring Recommendations

• Enable verbose logging for the synology-chat extension to capture all incoming sender IDs and authorization decisions
• Set up alerts for any configuration changes to dmPolicy or allowedUserIds settings
• Monitor for unusual patterns of agent dispatch volume or timing from the Synology Chat channel
• Regularly audit the list of users who have successfully triggered bot actions against the intended allowlist configuration

How to Mitigate CVE-2026-31998

Immediate Actions Required

• Upgrade OpenClaw to a patched version that includes the security fixes from commits 0ee30361b8f6ef3f110f3a7b001da6dd3df96bb5 and 7655c0cb3a47d0647cbbf5284e177f90b4b82ddb
• Review all synology-chat configurations and ensure allowedUserIds contains explicit user IDs if using dmPolicy="allowlist"
• Temporarily switch to dmPolicy="open" only if you intend to allow all users; otherwise, populate the allowlist with authorized user IDs
• Audit logs for any unauthorized access that may have occurred during the vulnerable window

Patch Information

Security patches are available via two GitHub commits that address this authorization bypass vulnerability. The first commit and second commit implement a fail-closed approach where an empty allowlist now blocks all senders instead of allowing all. Additionally, a configuration warning has been added to alert administrators when dmPolicy="allowlist" is configured with an empty allowedUserIds array. Full details are available in the GitHub Security Advisory (GHSA-gw85-xp4q-5gp9).

Workarounds

• If unable to patch immediately, ensure all allowedUserIds arrays contain at least one authorized user ID when using dmPolicy="allowlist"
• Switch to dmPolicy="open" only in non-production environments or where unrestricted access is acceptable
• Implement network-level access controls to restrict which senders can reach the synology-chat integration endpoint
• Consider disabling the synology-chat plugin entirely until the patch can be applied if the integration is not critical

// PATCHED CODE - Fail-closed approach
/**
 * Check if a user ID is in the allowed list.
 * Allowlist mode must be explicit; empty lists should not match any user.
 */
export function checkUserAllowed(userId: string, allowedUserIds: string[]): boolean {
  return allowedUserIds.includes(userId);  // Empty array now correctly blocks all
}

// Configuration warning added in channel.ts
if (account.dmPolicy === "allowlist" && account.allowedUserIds.length === 0) {
  warnings.push(
    '- Synology Chat: dmPolicy="allowlist" with empty allowedUserIds blocks all senders. Add users or set dmPolicy="open".',
  );
}

Source: GitHub Commit Update