The NEEDBITS macro in the inflate_dynamic function in inflate.c for unzip can be invoked using invalid buffers, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unknown vectors that trigger a free of uninitialized or previously-freed data.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.