CVE-2021-34856

Name: CVE-2021-34856
Creator: NVD / NIST
Published: 2021-10-25T17:15:08.227+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 0.26%

Last modified Jun 17, 2026

CVE-2021-34856 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.1.3 (49160). An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability. EPSS estimates a 0.26% chance of exploitation in the next 30 days.

Description

This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.1.3 (49160). An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the virtio-gpu virtual device. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the hypervisor. Was ZDI-CAN-13581.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS Probability

0.26%

17.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Parallels	Parallels Desktop	16.1.3

References

https://kb.parallels.com/125013Patch, Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-938/Third Party Advisory, VDB Entry
https://kb.parallels.com/125013Patch, Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-21-938/Third Party Advisory, VDB Entry

Timeline

Published: Oct 25, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-34856?

How severe is CVE-2021-34856?

CVE-2021-34856 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 0.26% probability of exploitation in the next 30 days.

How do I fix CVE-2021-34856?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-34856?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST