A denial of service flaw was found in the way syslog-ng processed certain log patterns, when 'global' flag was speficied and PCRE backend was used for matching. A remote attacker could use this flaw to cause excessive memory use by the syslog-ng process via specially-crafted pattern.

References: [1] http://www.securityfocus.com/bid/47800/info [2] https://lists.balabit.hu/pipermail/syslog-ng/2011-May/016576.html

Upstream patch: [3] http://git.balabit.hu/?p=bazsi/syslog-ng-3.2.git;a=commit;h=09710c0b105e579d35c7b5f6c66d1ea5e3a3d3ff

The compilebranch function in pcrecompile.c in PCRE 8.x before 8.39 and pcre2compile.c in PCRE2 before 10.22 mishandles patterns containing an (ACCEPT) substring in conjunction with nested parentheses, which allows remote attackers to execute arbitrary code or cause a denial of service (stack-based buffer overflow) via a crafted regular expression, as demonstrated by a JavaScript RegExp object encountered by Konqueror, aka ZDI-CAN-3542.