Treason uncloaked!

[debian-user@mediaforest.net]

Hello everybody.
There are now many years I find regularly this kind of error messages in 
my logs :
kernel: TCP: Treason uncloaked! Peer x.x.x.x:x/80 shrinks window x:x. 
Repaired.

There are many years, I search the web about that, and that I don't find 
anything excepted other people asking the same thing than me...

Perhaps someone of you know the answer to these questions :
what does mean this error message ?
What causes it ?
Is this dangerous for the system ?
If it's not really dangerous, why this message is so frightenning ?

And the main question : How is it possible that there isn't any 
documentation, nor answer, nor anything about this, only questions 
similar to mine ?

Thanks for any information about that