OpenClaw (npm package openclaw) versions >= 2026.6.6 and < 2026.8.1 apply the SMS webhook invalid-request rate limit before Twilio signature verification and identify clients only by the raw proxy socket address. In deployments where the SMS/Twilio webhook sits behind a trusted reverse proxy or tunnel so that multiple external clients share one socket address, an unauthenticated remote sender can exhaust the shared pre-authentication rate-limit budget with invalid requests, causing subsequent correctly signed Twilio callbacks to receive HTTP 429 responses. The result is temporary inbound SMS loss while the shared window remains exhausted; the attacker cannot forge a callback or access message data. Fixed in 2026.8.1.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html