CVE-2026-100572: OpenClaw Synology Chat Webhook DOS Flaw

CVE-2026-100572 Overview

CVE-2026-100572 is a denial of service vulnerability in OpenClaw affecting versions >= 2026.3.25 and < 2026.8.1. The flaw lies in how OpenClaw applies invalid-token rate limiting for Synology Chat webhooks before authentication. The rate limit is keyed on the raw proxy socket address rather than the real client identity. When OpenClaw sits behind a trusted reverse proxy or tunnel, multiple external clients share one socket address. An unauthenticated attacker can exhaust the shared invalid-token budget. Legitimate Synology Chat webhook callbacks are then rejected until the rate-limit window expires. The vulnerability is categorized as uncontrolled resource consumption [CWE-400].

Critical Impact
Unauthenticated attackers can cause temporary loss of Synology Chat webhook availability by exhausting the shared invalid-token rate-limit budget behind a reverse proxy.

Affected Products

OpenClaw versions >= 2026.3.25
OpenClaw versions < 2026.8.1
OpenClaw deployments behind a trusted reverse proxy or tunnel sharing a socket address

Discovery Timeline

2026-09-26 - CVE-2026-100572 published to NVD
2026-09-28 - Last updated in NVD database

Technical Details for CVE-2026-100572

Vulnerability Analysis

OpenClaw enforces an invalid-token rate limit for Synology Chat webhook requests before the sender is authenticated. The counter is keyed on the raw socket address of the incoming TCP connection. In deployments where OpenClaw sits behind a reverse proxy, tunnel, or load balancer, every forwarded request appears to originate from the proxy's socket address. All external senders share a single bucket for invalid-token attempts.

An unauthenticated attacker can submit repeated webhook requests with invalid tokens. Each failed attempt consumes the shared budget tied to the proxy socket. Once the budget is exhausted, OpenClaw rejects every subsequent Synology Chat webhook request routed through that proxy. Legitimate Synology Chat callbacks are blocked until the rate-limit window expires. The attacker cannot obtain a valid token, authenticate as another user, or read channel contents.

Root Cause

The root cause is improper client identification during pre-authentication rate limiting. OpenClaw relies on the raw transport-layer peer address rather than parsing forwarded headers such as X-Forwarded-For or validated proxy-provided identity. Combining shared infrastructure with a per-source counter produces a resource-exhaustion condition [CWE-400].

Attack Vector

The attack is network-reachable and requires no authentication or user interaction. An attacker only needs the ability to send HTTP requests to the OpenClaw Synology Chat webhook endpoint through the same reverse proxy used by legitimate clients. The attacker submits repeated requests containing invalid webhook tokens until the shared invalid-token budget is exhausted, denying service to other tenants sharing that proxy socket. See the GitHub Security Advisory GHSA-fw6q-2frm-jxxr and the VulnCheck Denial of Service Advisory for additional technical context.

Detection Methods for CVE-2026-100572

Indicators of Compromise

Elevated rates of rejected Synology Chat webhook callbacks with invalid-token errors in OpenClaw logs.
A single upstream proxy socket address accounting for a disproportionate share of invalid-token failures.
Legitimate Synology Chat integrations reporting delivery failures that recover after the rate-limit window elapses.

Detection Strategies

Correlate OpenClaw webhook rejection logs with reverse proxy access logs to identify bursts of invalid-token requests from the same forwarded client.
Alert on sustained invalid-token error rates exceeding a baseline for any single proxy source address.
Baseline normal Synology Chat webhook volume per channel and flag deviations that coincide with rate-limit exhaustion events.

Monitoring Recommendations

Forward OpenClaw application logs and reverse proxy logs to a centralized logging platform for correlation and retention.
Track rate-limit counter saturation events and surface them as operational alerts to the service owner.
Monitor the OpenClaw project repository and advisory feeds for additional guidance related to CVE-2026-100572.

How to Mitigate CVE-2026-100572

Immediate Actions Required

Upgrade OpenClaw to version 2026.8.1 or later, which contains the fix for CVE-2026-100572.
Inventory all OpenClaw instances deployed behind reverse proxies, tunnels, or load balancers and prioritize them for patching.
Review reverse proxy configuration to ensure trusted forwarded-client headers are passed to OpenClaw.

Patch Information

The issue is fixed in OpenClaw version 2026.8.1. Refer to the GitHub Security Advisory GHSA-fw6q-2frm-jxxr for release notes and remediation guidance.

Workarounds

Terminate TLS and route traffic through a proxy that enforces per-client identification before requests reach OpenClaw.
Restrict the OpenClaw webhook endpoint to allow-listed source networks associated with trusted Synology Chat deployments.
Deploy a web application firewall rule that limits invalid-token request bursts per real client IP extracted from forwarded headers.

bash

# Configuration example
# Upgrade OpenClaw to the fixed release
# Replace with the appropriate package manager or deployment command for your environment
# e.g., pip, container image pin, or source checkout tag

# Pin the container image to the fixed version
docker pull openclaw/openclaw:2026.8.1

# Verify the running version
openclaw --version