What is the CVSS score of CVE-2021-43555?

CVE-2021-43555 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 38.0%.

Is there a patch available for CVE-2021-43555?

Yes, a patch is available for CVE-2021-43555. Update the affected software to the latest version immediately.

Mydesigner CVE-2021-43555

HIGH

Relative Path Traversal (CWE-23)

2021-11-19 ics-cert@hq.dhs.gov

RCE Path Traversal Mydesigner Myscada

7.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-23 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V5 - File Handling Relative path traversal prevention
Impact	CVSS score of 7.8 (HIGH). Attack characteristics: local attack vector, low complexity, no privileges required, user interaction required.
Exploit ScenarioDerived	Successful exploitation could compromise the high-severity affected system.

This Week Schedule remediation this week. Why: HIGH severity + EPSS > 10%.

Patch available 38.0% exploitation probability (EPSS)

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AnalysisAI

mySCADA myDESIGNER Versions 8.20.0 and prior fails to properly validate contents of an imported project file, which may make the product vulnerable to a path traversal payload. Rated high severity (CVSS 7.8), this vulnerability is no authentication required, low attack complexity.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified under CWE-23. mySCADA myDESIGNER Versions 8.20.0 and prior fails to properly validate contents of an imported project file, which may make the product vulnerable to a path traversal payload. This vulnerability may allow an attacker to plant files on the file system in arbitrary locations or overwrite existing files, resulting in remote code execution. Affected products include: Myscada Mydesigner.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 7.8 HIGH

AV:L/AC:L/PR:N/UI:R/S:U/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

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

mySCADA myDESIGNER Versions 8.20.0 and prior fails to properly validate contents of an imported project file, which may make the product vulnerable to a path traversal payload. This vulnerability may allow an attacker to plant files on the file system in arbitrary locations or overwrite existing files, resulting in remote code execution.

Threat Intelligence Overview

EPSS Score

38.0%

Top 2% 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 38.0%

Patch available Yes

Active threat No

Deciding rule

HIGH severity + EPSS > 10%

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.