Vulnerability identifier: #VU6999

Vulnerability risk: Low

CVSSv3.1: 5.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-6671

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Cisco Email Security Appliance
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: Cisco Systems, Inc

Description
The vulnerability allows remote unauthenticated attacker to bypass configured filters on the device.

The weakness exists in the email message scanning of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) due to improper input validation of an email with an attachment and modified Multipurpose Internet Mail Extensions (MIME) header. A remote attacker can send a malformed email message with an attachment to bypass configured message filters.

Mitigation
Update to version 9.8.1-015 or 10.0.2-020.

Vulnerable software versions

Cisco Email Security Appliance: 9.7.1 066 - 10.0.1 087

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External links
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170607-esa1

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.