boazsegev facil.io WebSocket Frame websocket_parser.h websocket_on_protocol_error input validation

A flaw has been found in boazsegev facil.io up to 0.7.4. Affected is the function websocket_on_protocol_error in the library lib/facil/http/parsers/websocket_parser.h of the component WebSocket Frame Parser. This manipulation of the argument on_message causes improper input validation. The attack can be initiated remotely. The exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.