What is the CVSS score of CVE-2020-13364?

CVE-2020-13364 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 1.2%.

Nas326 Firmware CVE-2020-13364

HIGH

2020-08-06 cve@mitre.org

Information Disclosure Zyxel Nas326 Firmware Nas520 Firmware Nas540 Firmware Nas542 Firmware

8.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Impact	CVSS score of 8.8 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	This vulnerability can be exploited remotely over the network. Successful exploitation could compromise the high-severity affected system.

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

No patch listed yet 1.2% exploitation probability (EPSS)

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AnalysisAI

A backdoor in certain Zyxel products allows remote TELNET access via a CGI script. Rated high severity (CVSS 8.8), 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

A backdoor in certain Zyxel products allows remote TELNET access via a CGI script. This affects NAS520 V5.21(AASZ.4)C0, V5.21(AASZ.0)C0, V5.11(AASZ.3)C0, and V5.11(AASZ.0)C0; NAS542 V5.11(ABAG.0)C0, V5.20(ABAG.1)C0, and V5.21(ABAG.3)C0; NSA325 v2_V4.81(AALS.0)C0 and V4.81(AAAJ.1)C0; NSA310 4.22(AFK.0)C0 and 4.22(AFK.1)C0; NAS326 V5.21(AAZF.8)C0, V5.11(AAZF.4)C0, V5.11(AAZF.2)C0, and V5.11(AAZF.3)C0; NSA310S V4.75(AALH.2)C0; NSA320S V4.75(AANV.2)C0 and V4.75(AANV.1)C0; NSA221 V4.41(AFM.1)C0; and NAS540 V5.21(AATB.5)C0 and V5.21(AATB.3)C0. Affected products include: Zyxel Nas326 Firmware, Zyxel Nas520 Firmware, Zyxel Nas540 Firmware, Zyxel Nas542 Firmware.

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

Threat Intelligence Overview

EPSS Score

1.2%

Top 37% 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 1.2%

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

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +44

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.

Affected Products (CPE)NVD

cpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:nas520_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:nas540_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

More in Nas326 Firmware

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** UNSUPPORTED WHEN ASSIGNED ** The remote code execution vulnerability in the CGI program “file_upload-cgi” in Zyxel NA

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9.8 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the “setCookie” parameter in Zyxel NAS326 firmwar

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9.8 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the CGI program "remote_help-cgi" in Zyxel NAS326

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An eval injection vulnerability in the Python web server routing on the Zyxel NAS 326 version 5.21 and below allows a re

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Shell Metacharacter Injection in the package installer on Zyxel NAS 326 version 5.21 and below allows an authenticated a

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8.8 Apr 09

A plaintext password vulnerability in the Zyxel NAS 326 through 5.21 allows an elevated privileged user to get the admin

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6.7 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The improper privilege management vulnerability in the SUID executable binary in Zyxel N

CVE-2024-29976 MEDIUM This Month POC

6.5 Jun 04

** UNSUPPORTED WHEN ASSIGNED ** The improper privilege management vulnerability in the command “show_allsessions” in Zyx

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6.5 Apr 09

A directory traversal vulnerability in the file browser component on the Zyxel NAS 326 version 5.21 and below allows a l

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9.8 Sep 10

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CVE-2023-4474 CRITICAL Act Now

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CVE-2025-68613 HIGH POC

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References

Advisories & patches

ADVISORY https://www.zyxel.com/support/Zyxel-security-advisory-for-NAS-remote-access-vulnerability.shtml ADVISORY https://www.zyxel.com/us/en/support/security_advisories.shtml

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GitHub PoC

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