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.