I don't think this is widely used, filing for completeness. Buffer overflow in the bufprint function in capiutil.c in libcapi, as used in Linux kernel 2.6.9 to 2.6.20 and isdn4k-utils, allows local users to cause a denial of service (crash) and possibly gain privileges via a crafted CAPI packet.
this is a duplicate of the resolved bug 170870
*** This bug has been marked as a duplicate of bug 170870 ***