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Cisco Bug: CSCvu35999 - Cisco Email Security Appliance Denial of Service Vulnerability

Last Modified

Oct 16, 2020

Products (1)

  • Cisco IronPort Email Security Appliance Software

Known Affected Releases


Description (partial)

A vulnerability in the Transport Layer Security (TLS) protocol implementation of Cisco AsyncOS software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to cause high CPU usage on an affected device, resulting in a denial of service (DoS) condition.

The vulnerability is due to inefficient processing of incoming TLS traffic. An attacker could exploit this vulnerability by sending a series of crafted TLS packets to an affected device. A successful exploit could allow the attacker to trigger a prolonged state of high CPU utilization. The affected device would still be operative, but response time and overall performance may be degraded.

There are no workarounds that address this vulnerability.

This advisory is available at the following link:

At the time of publication, this vulnerability affected Cisco ESA software releases 13.5.1-277 and earlier.
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