The Microsoft Security Update
896358
not only fixes a vulnerability in HTML help, it prevents HTML
help files from execution, if the CHM file is installed on a
network drive. CHM files installed locally continue to work.
This affects all HTML Help
files!
Symptoms:
When you open a CHM file from a UNC path or from a network drive
even if the network drive is mapped to a drive letter, the HTML
Help viewer opens and instead of displaying the topic, it displays
an error message "Action cancelled" in the topic pane.
The Microsoft
Security Update 896358 restricts execution of HTML
Help files to the local machine zone. In fact it disables half of
the CHM files in the world (the other half is installed on the C:
drive).
How to fix this
problem:
Re-enable the
execution of HTML Help files:
Open the Windows registry and go to the key
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\HHRestrictions
Set the value of MaxAllowedZone to 1.
Go to the key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\HTMLHelp\1.x\ItssRestrictions
and also set the value of MaxAllowedZone to 1.
"MaxAllowedZone"=dword:00000001 means that access is
granted to the local zone (local harddrive) and the local intranet
zone (network).
You must perform these steps on
every client computer in your organization to enable HTML
Help for you.
Quick fix method:
Unzip and Run KB896358_FIX.reg, which will
merges the registry setting contained in this file into the
registry of the PC. This modifies the registry settings
as explained above.
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