#VU25 Null pointer dereference in ngx_chain_to_iovec() in nginx - CVE-2016-4450

Vulnerability identifier: #VU25

Vulnerability risk: Medium

CVSSv4.0: 6.6 [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:U/U:Green]

CVE-ID: CVE-2016-4450

CWE-ID: CWE-829

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
nginx
Server applications / Web servers

Vendor: NGINX

Description

The vulnerability allows a remote attacker to cause denial of service conditions on the target system.

The vulnerability exists due to an access control error in the ngx_chain_to_iovec() function, when saving the client request body to a temporary file. A remote unauthenticated attacker can cause a null pointer dereference in the ngx_chain_to_iovec() function by sending specially crafted data.

Successful exploitation of this vulnerability may lead to the crash of a worker process.

Mitigation

The vendor has issued a fix (1.10.1, 1.11.1).

Patch for nginx 1.9.13 - 1.11.0 can be found here:

http://nginx.org/download/patch.2016.write.txt

Patch for older nginx versions (1.3.9 - 1.9.12):

http://nginx.org/download/patch.2016.write2.txt

Vulnerable software versions

nginx: 1.3.9 - 1.3.16, 1.4.0 - 1.4.7, 1.5.0 - 1.5.13, 1.6.0 - 1.6.3, 1.7.0 - 1.7.12, 1.8.0 - 1.8.1, 1.9.0 - 1.9.15, 1.10.0 - 1.11.0

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External links
https://mailman.nginx.org/pipermail/nginx-announce/2016/000179.html?_ga=1.247559623.1519132670.1455108729

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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.