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CERT Coordination Center

Zyxel P660 series modem/router denial of service vulnerability

Vulnerability Note VU#893726

Original Release Date: 2014-04-01 | Last Revised: 2014-04-01


Zyxel P660 series modem/router contains a denial of service vulnerability when parsing a high volume of SYN packets on the web management interface.


It has been reported that Zyxel P660 series modem/router (and possibly other models which share the same core firmware) fail to parse a high volume of SYN packets on the web management interface correctly causing the device to reboot. By default, the device runs a web management interface on port tcp/80 which is accessible remotely (LAN and WAN sides).


An unauthenticated attacker can cause the device to reboot and become unavailable by sending a stream of SYN packets to the device's web management interface.


We are currently unaware of a practical solution to this problem.

Restrict Network Access

As a general good security practice, only allow connections from trusted hosts and networks if possible. Restricting access would prevent an attacker from connecting to the service from a blocked network location.

Vendor Information

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Notified:  June 17, 2013 Updated:  July 31, 2013



Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.


There are no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

CVSS Metrics

Group Score Vector
Base 7.1 AV:N/AC:M/Au:N/C:N/I:N/A:C
Temporal 5.4 E:U/RL:U/RC:UC
Environmental 4.1 CDP:ND/TD:M/CR:ND/IR:ND/AR:ND



Thanks to Alex French for reporting this vulnerability.

This document was written by Michael Orlando.

Other Information

CVE IDs: CVE-2013-3588
Date Public: 2013-08-06
Date First Published: 2014-04-01
Date Last Updated: 2014-04-01 14:43 UTC
Document Revision: 11

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