Although no attacks have been reported, Ledger wallet holders may be susceptible to attacks by what is called 'Man In the Middle', a technique through which hackers/malware modifies the receiving address for a transaction before the user performs a transaction.
However this can be avoided by following clicking on the 'monitor' icon before sending coins
read the story:
http://www.altcointoday.com/ledger-addresses-man-middle-attack-threatens-millions-hardware-wallets/
Protect yourself - be informed!!