#VU18374 NULL pointer dereference in memcached - CVE-2019-11596

Vulnerability identifier: #VU18374

Vulnerability risk: Medium

CVSSv4.0: 7.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2019-11596

CWE-ID: CWE-476

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
memcached
Server applications / Web servers

Vendor: Memcached

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

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External links
https://github.com/memcached/memcached/commit/d35334f368817a77a6bd1f33c6a5676b2c402c02
https://github.com/memcached/memcached/compare/ee1cfe3...50bdc9f
https://github.com/memcached/memcached/issues/474

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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. However, proof of concept for this vulnerability is available.