Multiple heap-based buffer underflows in the readPostBody function in cgiutil.c in mapserv in MapServer 4.x through 4.10.4 and 5.x before 5.4.2 allow remote attackers to execute arbitrary code via (1) a crafted Content-Length HTTP header or (2) a large HTTP request, related to an integer overflow that triggers a heap-based buffer overflow. NOTE: this issue reportedly exists because of an incomplete fix for CVE-2009-0840.
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.