What is the CVSS score of CVE-2021-27242?

CVE-2021-27242 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.3%.

Parallels Desktop CVE-2021-27242

HIGH

Out-of-bounds Write (CWE-787)

2021-03-29 zdi-disclosures@trendmicro.com

Buffer Overflow Memory Corruption Parallels Desktop Parallels

8.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-787 ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, write limits MITRE ATT&CK 2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 8.8 (HIGH). Attack characteristics: local attack vector, low complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	A local attacker with access to the system could write data beyond allocated buffer boundaries leading to code execution or crashes.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAI

This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.0.1-48919. Rated high severity (CVSS 8.8), this vulnerability is low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.0.1-48919. An attacker must first obtain the ability to execute low-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the Toolgate component. 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 code in the context of the hypervisor. Was ZDI-CAN-11926. Affected products include: Parallels Parallels Desktop.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

This vulnerability allows local attackers to escalate privileges on affected installations of Parallels Desktop 16.0.1-48919. An attacker must first obtain the ability to execute low-privileged code on the target guest system in order to exploit this vulnerability. The specific flaw exists within the Toolgate component. 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 code in the context of the hypervisor. Was ZDI-CAN-11926.

Threat Intelligence Overview

EPSS Score

0.3%

Top 81% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.3%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Small

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.