The Link Grammar Parser is "a syntactic parser of English, based on link grammar, an original theory of English syntax. Given a sentence, the system assigns to it a syntactic structure, which consists of a set of labeled links connecting pairs of words. The parser also produces a "constituent" representation of a sentence (showing noun phrases, verb phrases, etc.)" Secunia Research has discovered a vulnerability in Link Grammar, which can be exploited by malicious people to compromise an application using the affected code.

http://www.securiteam.com/unixfocus/6P0042AKAI.html