Off-by-one error in the inflate function in Zlib.xs in Compress::Raw::Zlib Perl module before 2.017 as used in AMaViS SpamAssassin and possibly other products allows context-dependent attackers to cause a denial of service (hang or crash) via a crafted zlib compressed stream that triggers a heap-based buffer overflow as exploited in the wild by Trojan.Downloader-71014 in June 2009.