HAProxy 1.4 before 1.4.24 and 1.5 before 1.5-dev19, when configured to use hdr_ip or other "hdr_*" functions with a negative occurrence count, allows remote attackers to cause a denial of service (negative array index usage and crash) via an HTTP header with a certain number of values, related to the MAX_HDR_HISTORY variable.
Buffer overflow in HAProxy 1.4 through 1.4.22 and 1.5-dev through 1.5-dev17, when HTTP keep-alive is enabled, using HTTP keywords in TCP inspection rules, and running with rewrite rules that appends to requests, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via crafted pipelined HTTP requests that prevent request realignment from occurring.
Buffer overflow in the trash buffer in the header capture functionality in HAProxy before 1.4.21, when global.tune.bufsize is set to a value greater than the default and header rewriting is enabled, allows remote attackers to cause a denial of service and possibly execute arbitrary code via unspecified vectors.