CVE-2026-41400
Denial of Service via Oversized WebSocket Frames in OpenClaw Voice-Call
Publication date: 2026-04-28
Last updated on: 2026-04-30
Assigner: VulnCheck
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| openclaw | openclaw | to 2026.3.31 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-770 | The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2026-41400 affects OpenClaw versions prior to 2026.3.31 and involves a vulnerability in the voice-call component where large WebSocket frames are parsed before proper start validation occurs.
Remote attackers can send oversized pre-start WebSocket frames, which the system processes without limits or throttling, leading to excessive resource consumption.
This vulnerability is a result of an incomplete fix for a previous issue (CVE-2026-32062) and is classified under CWE-770 (Allocation of Resources Without Limits or Throttling).
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
The provided information does not specify any direct impact of CVE-2026-41400 on compliance with common standards and regulations such as GDPR or HIPAA.
How can this vulnerability impact me? :
The vulnerability allows remote attackers to cause excessive resource consumption by sending oversized WebSocket frames before the voice-call component starts validation.
This can lead to denial of service (DoS), where legitimate users may be unable to use the voice-call feature or the system may become unresponsive.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability involves the voice-call component of OpenClaw parsing oversized WebSocket frames before start validation, which can lead to resource consumption and denial of service. Detection would involve monitoring for unusually large WebSocket frames, especially pre-start frames, being sent to the voice-call service.
Since the vulnerability is related to oversized WebSocket frames, network detection could include capturing WebSocket traffic and inspecting frame sizes. Tools like Wireshark or tcpdump can be used to capture traffic, and custom scripts or WebSocket frame analyzers can be used to identify frames exceeding normal size thresholds (e.g., larger than 64 KB).
Suggested commands to capture and analyze WebSocket traffic might include:
- Use tcpdump to capture traffic on the relevant port (replace <port> with the actual port): tcpdump -i any port <port> -w capture.pcap
- Open the capture in Wireshark and filter for WebSocket frames: websocket
- In Wireshark, inspect the 'Payload length' field of WebSocket frames to identify frames larger than 64 KB.
Alternatively, if you have access to the OpenClaw server logs or can instrument the WebSocket server, you can add logging or monitoring to detect when oversized frames are received or when connections are closed with WebSocket close code 1009 (message too big), which indicates rejection of oversized frames as per the patch.
What immediate steps should I take to mitigate this vulnerability?
The primary mitigation step is to upgrade OpenClaw to version 2026.3.31 or later, where the vulnerability has been fixed by enforcing a maximum inbound WebSocket frame size of 64 KB at the WebSocket server level.
This fix ensures that oversized pre-start WebSocket frames are rejected immediately before any parsing or application-level validation, preventing resource exhaustion and denial of service.
If upgrading immediately is not possible, consider implementing network-level protections such as WebSocket frame size limits or rate limiting on the voice-call service ports to reduce the risk of resource exhaustion.
Monitoring for and blocking connections that send oversized frames or exhibit suspicious behavior related to WebSocket traffic can also help mitigate exploitation attempts.