CVE-2026-41407: OpenClaw Information Disclosure Flaw

CVE-2026-41407 Overview

OpenClaw before version 2026.4.2 contains a timing side channel vulnerability in shared-secret comparison call sites. The vulnerable code uses early length-mismatch checks instead of fixed-length comparison helpers, allowing attackers to measure timing differences and leak secret-length information. This weakness undermines the constant-time handling required for secure shared secret operations.

Critical Impact

Attackers can exploit timing differences in secret comparisons to infer secret lengths, potentially enabling targeted brute-force attacks or further cryptographic weaknesses.

Affected Products

• OpenClaw versions prior to 2026.4.2

Discovery Timeline

• 2026-04-28 - CVE-2026-41407 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2026-41407

Vulnerability Analysis

This vulnerability falls under CWE-208 (Observable Timing Discrepancy), a class of cryptographic side-channel vulnerabilities. The core issue resides in how OpenClaw compares shared secrets during authentication and validation workflows. When comparing secrets, the implementation performs an early length check that returns immediately if the lengths differ, rather than using a constant-time comparison that processes the full length regardless of match status.

This timing discrepancy creates an observable side channel. An attacker who can repeatedly submit authentication attempts and precisely measure response times can deduce whether their submitted secret has the correct length. Once the correct length is known, the attacker can proceed with more targeted attacks against the secret value itself.

The vulnerability affects multiple extension modules within OpenClaw, including the BlueBubbles and Feishu integrations, where webhook secret validation occurs.

Root Cause

The root cause is the use of standard comparison operations that exhibit variable execution time based on input characteristics. Instead of employing constant-time comparison functions like safeEqualSecret from the OpenClaw plugin SDK, the affected code paths imported timingSafeEqual from Node.js crypto but did not apply it consistently across all comparison sites. Early-exit patterns in length checking created measurable timing differences that leak information about secret lengths.

Attack Vector

The attack vector is network-based, requiring the attacker to have the ability to send requests to the vulnerable OpenClaw endpoints and measure response timing with sufficient precision. While the attack complexity is high due to the need for statistical analysis of multiple timing measurements, it requires no authentication or user interaction.

An attacker would:

1. Send multiple requests with secrets of varying lengths
2. Measure the response times for each request
3. Statistically analyze timing differences to determine the correct secret length
4. Use the leaked length information to narrow down brute-force attacks

// Vulnerable code pattern (before fix) - BlueBubbles extension
-import { timingSafeEqual } from "node:crypto";
 import type { IncomingMessage, ServerResponse } from "node:http";
+import { safeEqualSecret } from "openclaw/plugin-sdk/browser-support";
 import { createBlueBubblesDebounceRegistry } from "./monitor-debounce.js";
 import { normalizeWebhookMessage, normalizeWebhookReaction } from "./monitor-normalize.js";
 import { logVerbose, processMessage, processReaction } from "./monitor-processing.js";

Source: GitHub Commit

// Patched code - Feishu extension also updated to use consistent helper
 import * as http from "http";
 import crypto from "node:crypto";
 import * as Lark from "@larksuiteoapi/node-sdk";
+import { safeEqualSecret } from "openclaw/plugin-sdk/browser-support";
 import {
   applyBasicWebhookRequestGuards,
   isRequestBodyLimitError,

Source: GitHub Commit

Detection Methods for CVE-2026-41407

Indicators of Compromise

• Unusual patterns of failed authentication attempts with secrets of incrementally varying lengths
• High-frequency requests to webhook endpoints from single sources with minimal payload variations
• Statistical anomalies in authentication request timing from specific IP addresses

Detection Strategies

• Monitor for rapid sequences of authentication failures that may indicate timing measurement attacks
• Implement rate limiting and anomaly detection on webhook validation endpoints
• Deploy application performance monitoring to detect unusual response time analysis patterns

Monitoring Recommendations

• Enable detailed logging for all shared secret comparison operations in affected extensions
• Set up alerts for authentication endpoints receiving unusually high request volumes
• Monitor for reconnaissance patterns targeting BlueBubbles and Feishu integration endpoints

How to Mitigate CVE-2026-41407

Immediate Actions Required

• Upgrade OpenClaw to version 2026.4.2 or later immediately
• Review all webhook configurations for BlueBubbles and Feishu integrations
• Rotate shared secrets for any integrations that may have been exposed to timing attacks
• Implement additional rate limiting on webhook endpoints as a defense-in-depth measure

Patch Information

The fix is available in OpenClaw version 2026.4.2. The patch replaces inconsistent timing-safe comparison implementations with the centralized safeEqualSecret helper from openclaw/plugin-sdk/browser-support. This ensures all shared secret comparisons use constant-time operations that do not leak length information.

For detailed information, see the GitHub Security Advisory and VulnCheck Advisory.

Workarounds

• Implement network-level rate limiting to reduce the statistical viability of timing attacks
• Deploy a reverse proxy or WAF with request rate limiting capabilities in front of affected endpoints
• Consider temporary disabling of affected webhook integrations until patching is complete

# Example: Rate limiting webhook endpoints using nginx
# Add to nginx configuration for OpenClaw
limit_req_zone $binary_remote_addr zone=webhook_limit:10m rate=10r/s;

location /api/webhooks/ {
    limit_req zone=webhook_limit burst=20 nodelay;
    proxy_pass http://openclaw_backend;
}