Denial of Service

Overview

Affected versions of uws do not properly handle large websocket messages when permessage-deflate is enabled, which may result in a denial of service condition.

If uws recieves a 256Mb websocket message when permessage-deflate is enabled, the server will compress the message prior to executing the length check, and subsequently extract the message prior to processing. This can result in a situation where an excessively large websocket message passes the length checks, yet still gets cast from a Buffer to a string, which will exceed v8’s maximum string size and crash the process.

Recommendation

Update to version 0.10.9 or later.

Alternatively, disable permessage-deflate.

References

• Commit #37deefd
• GitHub Advisory