Public Vulnerability Reports

Clam AntiVirus ClamAV CHM Chunk Name Length DoS Vulnerability



Clam AntiVirus is a multi-platform GPL anti-virus toolkit. The main
purpose of which is integration into electronic mail servers. More
information about ClamAV can be found at Microsoft
Compressed HTML Help (CHM) files are commonly used for windows based
software documentation.


Remote exploitation of a input validation vulnerability in Clam
AntiVirus's ClamAV could allow attackers to crash the virus scanning

The vulnerability specifically exists due to improper handling of an
specially crafted CHM file. While processing such a file, ClamAV may
attempt to read an invalid memory location resulting in abnormal
termination of the scanning service.


Successful exploitation could allow an attacker to crash the ClamAV
virus scanning service. Exploitation requires that attackers send a
specially constructed CHM file through an e-mail gateway or personal
anti-virus client using the ClamAV scanning engine.


iDefense has confirmed this vulnerability affects Clam AntiVirus ClamAV
v0.88.4. All prior versions that implement CHM file scanning are
suspected to be vulnerable.


iDefense is unaware of any effective workarounds for this issue.


The ClamAV team has addressed this vulnerability within version 0.88.5.


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-5295 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


09/28/2006 Initial vendor notification
09/29/2006 Initial vendor response
10/10/2006 Second vendor notification
10/15/2006 Coordinated public disclosure


This vulnerability was reported to iDefense by Damian Put and an
anonymous researcher.

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Copyright © 2006 Verisign, Inc.

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