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Cisco Email Security Appliance Email Scanner Denial of Service Vulnerability

Advisory ID: cisco-sa-20151104-esa2

Revision 1.0

For Public Release 2015 November 4 16:00 UTC (GMT)

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Summary
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A vulnerability in the email message filtering feature of Cisco AsyncOS 
for Cisco Email Security Appliance (ESA) could allow an unauthenticated, 
remote attacker to cause an ESA device to become unavailable due to a 
denial of service (DoS) condition.

The vulnerability is due to improper input validation when an email 
attachment contains corrupted fields and is filtered by the ESA. An 
attacker could exploit this vulnerability by sending a crafted email 
with an attachment to the ESA. A successful exploit could allow the 
attacker to cause a DoS condition. While the attachment is being
filtered, memory is consumed at at high rate until the filtering 
process restarts. When the process restarts, it will resume processing 
the same malformed attachment and the DoS condition will continue. 
Cisco has released software updates that address this vulnerability. 
There are no workarounds that mitigate this vulnerability.

This advisory is available at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151104-esa2

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