Linear cryptanalysis is a procedure for attacking block ciphers using plaintext-ciphertext pairs. However, it requires substantially more than one pair. Here's a paper that requires either 2^21 or 2^47 different pairs depending on the version of DES used. This may not be the most up to date, but the number of pairs needed is still considerable.
There are stronger attacks on DES, such as differential cryptanalysis, however they generally require access to an encryption oracle, i.e. that the attacker can choose plaintext pairs and get the resultant ciphertext.
EDIT: I misunderstood this to be about the DES cipher itself. See Tom Leak's post.