The Link Grammar parser is a syntactic parser of English, based on link grammar, an original theory of English syntax.
Alin Rad Pop from Secunia Research discovered a boundary error in the function separate_sentence() in file tokenize.c when processing an overly long word which might lead to a stack-based buffer overflow.
A remote attacker could entice a user to parse a specially crafted sentence, resulting in the remote execution of arbitrary code with the privileges of the user running the application. Note that this vulnerability may be triggered by an application using Link Grammar to parse sentences (e.g. AbiWord).
There is no known workaround at this time.
All Link Grammar users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-libs/link-grammar-4.2.4-r1"