CVE-2026-100558 OpenClaw before 2026.8.1 Resource Exhaustion via WebSocket Upgrade
Unauthenticated attackers can cause denial of service in OpenClaw by exhausting listener resources via malformed WebSocket upgrade requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-100558?
CVE-2026-100558 is a high-severity denial of service vulnerability in OpenClaw, published on 26 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
OpenClaw versions before 2026.8.1 contain a resource exhaustion vulnerability in the Gateway listener that allows unauthenticated clients to retain response sockets by sending WebSocket upgrade requests without matching connection semantics. Attackers can repeatedly send malformed upgrade requests to exhaust listener resources and cause denial of service without consuming the WebSocket pre-auth connection budget.
Weakness: CWE-400
Which versions are affected by CVE-2026-100558?
How do I fix CVE-2026-100558?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-100558 being exploited?
There is no known exploitation of CVE-2026-100558 in the wild and no public exploit code.
Sources
Also known as GHSA-4r25-35qc-fr6j, GHSA-5m65-2pj9-qf79, MINI-fphf-rjqv-26x3.