What is the CVSS score of CVE-2023-4397?

CVE-2023-4397 has a CVSS 3.1 base score of 4.4 (Medium). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.2%.

Zld CVE-2023-4397

MEDIUM

Classic Buffer Overflow (CWE-120)

2023-11-28 security@zyxel.com.tw

Buffer Overflow Zyxel Zld

4.4

CVSS 3.1 · Vendor: zyxel

View

Vulnerability Assessment

Weakness	CWE CWE-120 ASVS 5.0 V15 - Secure Coding and Architecture Buffer copy size validation MITRE ATT&CK 1 technique across 1 tactic: Execution 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 4.4 (MEDIUM). Attack characteristics: local attack vector, low complexity, high privileges required, no user interaction not required.
Exploit ScenarioDerived	A local attacker with access to the system could overflow a buffer to corrupt adjacent memory.

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

No patch listed yet 0.2% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAI

A buffer overflow vulnerability in the Zyxel ATP series firmware version 5.37, USG FLEX series firmware version 5.37, USG FLEX 50(W) series firmware version 5.37, and USG20(W)-VPN series firmware. Rated medium severity (CVSS 4.4), 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. Always validate buffer sizes before copy operations. Use bounded functions (strncpy, snprintf). Enable compiler protections.

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 as Buffer Copy without Size Check (CWE-120), which allows attackers to overflow a buffer to corrupt adjacent memory. A buffer overflow vulnerability in the Zyxel ATP series firmware version 5.37, USG FLEX series firmware version 5.37, USG FLEX 50(W) series firmware version 5.37, and USG20(W)-VPN series firmware version 5.37, could allow an authenticated local attacker with administrator privileges to cause denial-of-service (DoS) conditions by executing the CLI command with crafted strings on an affected device. Affected products include: Zyxel Zld. Version information: version 5.37.

Know when Zld gets its next vulnerability

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

Vendor (zyxel) PRIMARY 4.4 MEDIUM

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

Primary rating from Vendor (zyxel) · only source for this CVE.

CVSS VectorVendor: zyxel

Attack Vector

Local

Attack Complexity

Low

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

DescriptionCVE.org

A buffer overflow vulnerability in the Zyxel ATP series firmware version 5.37, USG FLEX series firmware version 5.37, USG FLEX 50(W) series firmware version 5.37, and USG20(W)-VPN series firmware version 5.37, could allow an authenticated local attacker with administrator privileges to cause denial-of-service (DoS) conditions by executing the CLI command with crafted strings on an affected device.

Threat Intelligence Overview

EPSS Score

0.2%

Top 86% 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 0.2%

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

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: +22

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.