CVE-2007-4556 in XWork
Summary
Struts support in OpenSymphony XWork before 1.2.3, and 2.x before 2.0.4, as used in WebWork and Apache Struts, recursively evaluates all input as an Object-Graph Navigation Language (OGNL) expression when altSyntax is enabled, which allows remote attackers to cause a denial of service (infinite loop) or execute arbitrary code via form input beginning with a "%{" sequence and ending with a "}" character.
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