Denial of service in memcached

1) NULL pointer dereference

EUVDB-ID: #VU18374

Risk: Medium

CVSSv3.1: 6.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2019-11596

CWE-ID: CWE-476 - NULL Pointer Dereference

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dreference error in the "lru mode" and "lru temp_ttl" commands when parsing specially crafted lru command messages passed passed to process_lru_command() function in memcached.c. A remote attacker can send a specially crafted HTTP request to the affected application and perform denial of service (DoS) attack.

Exploitation example:

echo -n "bHJ1IG1vZGUKb7G0AGxydWRl6gdtTk9UXw==" | base64 -d | nc 127.0.0.1 11211

Mitigation

Install update from vendor's website.

Vulnerable software versions

memcached: 1.5.0 - 1.5.13

External links

http://github.com/memcached/memcached/commit/d35334f368817a77a6bd1f33c6a5676b2c402c02
http://github.com/memcached/memcached/compare/ee1cfe3...50bdc9f
http://github.com/memcached/memcached/issues/474

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.