Memory leaking occurs in evaluate_LOGEVENTID() and evaluate_STR().
Both 1.8.x and 2.0.x has same memory leaking.

Zabbix Server memory leaks in evaluate_STR() and evaluate_LOGEVENTID() in "src/libs/zbxserver/evalfunc.c".
It doesn't free following strdup() memory in add_regexp_ex() called from evaluate_STR().
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(*regexps)[*regexps_num].name = strdup(name);
(*regexps)[*regexps_num].expression = strdup(expression);
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"clean_regexps_ex(regexps, regexps_num)" should be called before "zbx_free(regexps)" in evaluate_STR().

evaluate_STR() and evaluate_LOGEVENTID() are called when using "regexp()", "iregexp()", "logeventid()" trigger functions with "@" type regexp.
So, the memory leak occurs when using "regexp()", "iregexp()", "logeventid()" trigger functions with "@" type regexp.

I made patches for zabbix-1.8.15 and zabbix-2.0.4.
We thank you for your time and are hoping to receive feedback.