Cisco Security Advisory
Cisco Email Security Appliance Attachment Filter Bypass Vulnerability
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CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
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A vulnerability in the email message scanning of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass configured filters on the device.
The vulnerability is due to improper input validation of an email with an attachment and modified Multipurpose Internet Mail Extensions (MIME) header. An attacker could exploit this vulnerability by sending a malformed email message with an attachment. A successful exploit could allow the attacker to bypass configured message filters to drop the email. The email may not be RFC compliant. However, some mail clients could still allow users to read the email, which may not have been properly filtered by the device.
There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170607-esa1
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Vulnerable Products
This vulnerability affects Cisco Email Security Appliance. For information about affected software releases, consult the Cisco bug ID(s) at the top of this advisory.Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect Cisco Web Security Appliance (WSA) or Cisco Content Security Management Appliance (SMA).
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There are no workarounds that address this vulnerability.
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For information about fixed software releases, consult the Cisco bug ID(s) at the top of this advisory.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 1.0 Initial public release. - Final 2017-June-07
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