What is the CVSS score of CVE-2021-28815?

CVE-2021-28815 has a CVSS 3.1 base score of 4.9 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N. EPSS exploitation probability: 1.7%.

Myqnapcloud Link CVE-2021-28815

MEDIUM

Insecure Storage of Sensitive Information (CWE-922)

2021-06-16 security@qnapsecurity.com.tw

Information Disclosure Qnap Myqnapcloud Link

4.9

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-922 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V14 - Data Protection Secure storage of sensitive data
Impact	CVSS score of 4.9 (MEDIUM). Attack characteristics: network attack vector, low complexity, high privileges required, no user interaction not required.
Exploit ScenarioDerived	This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the medium-severity affected system.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

No patch listed yet 1.7% exploitation probability (EPSS)

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AnalysisAI

Insecure storage of sensitive information has been reported to affect QNAP NAS running myQNAPcloud Link. Rated medium severity (CVSS 4.9), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Apply vendor patches when available. Implement network segmentation and monitoring as interim mitigations.

Affects your stack

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Technical ContextAI · show details

This vulnerability is classified under CWE-922. Insecure storage of sensitive information has been reported to affect QNAP NAS running myQNAPcloud Link. If exploited, this vulnerability allows remote attackers to read sensitive information by accessing the unrestricted storage mechanism. This issue affects: QNAP Systems Inc. myQNAPcloud Link versions prior to 2.2.21 on QTS 4.5.3; versions prior to 2.2.21 on QuTS hero h4.5.2; versions prior to 2.2.21 on QuTScloud c4.5.4. Affected products include: Qnap Myqnapcloud Link. Version information: prior to 2.2.21.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 4.9 MEDIUM

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

DescriptionNVD

Insecure storage of sensitive information has been reported to affect QNAP NAS running myQNAPcloud Link. If exploited, this vulnerability allows remote attackers to read sensitive information by accessing the unrestricted storage mechanism. This issue affects: QNAP Systems Inc. myQNAPcloud Link versions prior to 2.2.21 on QTS 4.5.3; versions prior to 2.2.21 on QuTS hero h4.5.2; versions prior to 2.2.21 on QuTScloud c4.5.4.

Threat Intelligence Overview

EPSS Score

1.7%

Top 25% 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 MEDIUM

CISA KEV No

Public POC No

EPSS 1.7%

Patch available No

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

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

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +2

CVSS: +24

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.