bogofilter -- RFC 2047 decoder denial-of-service vulnerability

The bogofilter team has been provided with a test case of a
malformatted (non-conformant) RFC-2047 encoded word that can cause
bogofilter versions 0.92.7 and prior to try to write a NUL byte into
a memory location that is either one byte past the end of a flex
buffer or to a location that is the negative of the encoded word’s
start of payload data, causing a segmentation fault.