#VU13990 Race condition in Phusion Passenger - CVE-2018-12029

Vulnerability identifier: #VU13990

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-12029

CWE-ID: CWE-362

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Phusion Passenger
Server applications / Application servers

Vendor: Phusion B.V.

Description

The vulnerability allows a local attacker to gain elevated privileges.

The vulnerability exists due to a race condition that could occur when a non-standard passenger_instance_registry_dir setting  n the Nginx moduleis configured with insufficient permissions. A local attacker can replace a file with a symbolic link after the file has been created before the file has changed ownershipto gain elevated privileges on the system if the target of the symbolic link is a file that can be executed as root, such as the crontab file.

Mitigation
Update to version 5.3.2.

Vulnerable software versions

Phusion Passenger: 3.0.0 - 5.3.1

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External links
https://blog.phusion.nl/2018/06/12/passenger-5-3-2-various-security-fixes/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.