#VU60723 Time-of-check Time-of-use (TOCTOU) Race Condition in Parallels Desktop - CVE-2021-34986

Vulnerability identifier: #VU60723

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-2021-34986

CWE-ID: CWE-367

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Parallels Desktop
Operating systems & Components / Operating system package or component

Vendor: Parallels

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to Time-of-check Time-of-use condition within the Parallels Service. A local user can create a symbolic link, abuse the service to execute a file and gain elevated privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Parallels Desktop: before 17.1.0

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External links
https://www.zerodayinitiative.com/advisories/ZDI-22-385/
https://kb.parallels.com/en/125013

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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.