clamav 0.90.2 is now available via http://www.clamav.net
From their e-mail announcement :
Just FYI..."Changes in this release include some security fixes in CHM, CAB and PDF
code and better handling of network problems in freshclam.
Please see ChangeLog for complete list of changes.
**Important note**: on April 16th CHM, CAB and PDF handlers will be
disabled for 0.90 and 0.90.1 users through the dynamic engine
configuration module (DCONF). Please upgrade to 0.90.2 immediately."
If you have no idea how to upgrade or are a little shakey in doing the upgrade yourself, recommend that you wait for the Zimbra official release.
All others, http://www.zimbra.com/forums/administrators/1015-solved-howto-update-clamav.html#post5571
You probably should be blocking .CHM and .CAB files anyway IMHO, but you have to see and decide for yourselves.
.PDF's are a tough one ( Adobe Acrobat ) which is why this update is so important to do. After the 16th, .CHM, .CAB and .PDF files will no longer be scanned until clamav is upgraded.
Please read entire thread ( link above ) before proceeding.