IPFire versions prior to 2.29 (Core Update 198) contain a command injection vulnerability that allows an authenticated attacker to execute arbitrary commands as the user 'nobody' via multiple parameters when creating a Proxy report. When a user creates a Proxy report the application issues an HTTP POST to /cgi-bin/logs.cgi/calamaris.dat and reads the values of DAY_BEGIN, MONTH_BEGIN, YEAR_BEGIN, DAY_END, MONTH_END, YEAR_END, NUM_DOMAINS, PERF_INTERVAL, NUM_CONTENT, HIST_LEVEL, NUM_HOSTS, NUM_URLS, and BYTE_UNIT, which are interpolated directly into the shell invocation of the mkreport helper. Because these parameters are never sanitized for improper characters or constructs, a crafted POST can inject shell metacharacters into one or more fields, causing arbitrary commands to run with the privileges of the 'nobody' user.