#VU21600 PHP Code Injection in vBulletin - CVE-2019-17132

Vulnerability identifier: #VU21600

Vulnerability risk: High

CVSSv4.0: 7.4 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber]

CVE-ID: CVE-2019-17132

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
vBulletin
Web applications / Forum & blogging software

Vendor: vBulletin

Description

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

The vulnerability exists due to improper input validation in the " ajax/api/user/updateAvatar" endpoint when processing data passed via the "data[filedata" HTTP POST parameter. A remote authenticated attacker can send a specially crafted request to the Avatar update script and execute arbitrary PHP code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

vBulletin: 5.5.0 - 5.5.4

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External links
https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4423646-vbulletin-5-5-x-5-5-2-5-5-3-and-5-5-4-security-patch-level-2
https://karmainsecurity.com/pocs/CVE-2019-17132

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user 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.