ClamAV before 0.91.2, as used in Kolab Server 2.0 through 2.2beta1 and other products, allows remote attackers to cause a denial of service (application crash) via (1) a crafted RTF file, which triggers a NULL dereference in the cli_scanrtf function in libclamav/rtf.c; or (2) a crafted HTML document with a data: URI, which triggers a NULL dereference in the cli_html_normalise function in libclamav/htmlnorm.c.  NOTE: some of these details are obtained from third party information.