#VU3613 Use-after-free error in PHP - CVE-2016-5773

Vulnerability identifier: #VU3613

Vulnerability risk: High

CVSSv4.0: 8.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber]

CVE-ID: CVE-2016-5773

CWE-ID: CWE-416

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
PHP
Universal components / Libraries / Scripting languages

Vendor: PHP Group

Description
The vulnerability allows a remote attacker to execute arbitrary PHP code on the target system.

The vulnerability exists due to use-after-free in GC algorithm and unserialize. A remote attacker can create a specially crafted zval object and exploit the PHP process by taking over the EIP/RIP.

Successful exploitation of this vulnerability results in complete control over the vulnerable web application and execute arbitrary PHP code on the target system.

Mitigation
Update to version 5.6.23.

Vulnerable software versions

PHP: 5.5.36 - 5.5.37, 5.6.0 - 5.6.22

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External links
https://bugs.php.net/bug.php?id=72434

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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.