Value Encoding
...The CONNECT and CONNECTED frames do not
escape the carriage return, line feed or colon octets in order to remain backward
compatible with STOMP 1.0.
The backslash character is not mentioned here. In the same section, the backslash character encoding is specified:
\\ (octet 92 and 92) translates to \ (octet 92)
However it would make no sense to not exclude the backslash character from escaping in CONNECT and CONNECTED frames. Escaping it would break STOMP 1.0 compatibility.
Therefore I suggest to include the backshlash in the paragraph:
Value Encoding
...The CONNECT and CONNECTED frames do not
escape the backslash, carriage return, line feed, or colon octets in order to remain backward
compatible with STOMP 1.0.