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Published: 5 March 2018

Memcached version 1.5.5 contains an Insufficient Control of Network Message Volume (Network Amplification, CWE-406) vulnerability in the UDP support of the memcached server that can result in denial of service via network flood (traffic amplification of 1:50,000 has been reported by reliable sources). This attack appear to be exploitable via network connectivity to port 11211 UDP. This vulnerability appears to have been fixed in 1.5.6 due to the disabling of the UDP protocol by default.

From the Ubuntu Security Team

It was discovered that Memcached listened to UDP by default. A remote attacker could use this as part of a distributed denial of service attack.


in Ubuntu (and Debian) memcached is bound to the loppback
interface by default. However, if memcached is bound to other
interfaces, the UDP port is still enabled by default.
Ubuntu update is to disable listening on UDP by default. To
re-enable UDP, add '-U 11211' to /etc/memcached.conf and restart the
memcahced service.



CVSS 3 base score: 7.5


Package Release Status
Launchpad, Ubuntu, Debian
Released (1.5.6)
precise Does not exist

trusty Does not exist
(trusty was released [1.4.14-0ubuntu9.2])
Released (1.4.25-2ubuntu1.3)
Released (1.4.33-1ubuntu3.2)