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CVE-2023-6397

MEDIUM

5.3

CVSS Score

Published: February 20, 2024 at 01:19 AM UTC

Updated: June 17, 2026 at 06:50 AM UTC

40 products affected across 1 vendorUSG FLEX 200 firmwareUsg Flex 100W FirmwareUSG FLEX 700 firmware

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Severity

MEDIUM5.3

Exploit prediction

EPSS 0.3%

SSVC

No known exploit

Description

A null pointer dereference vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1 and USG FLEX series firmware versions from 4.50 through 5.37 Patch 1 could allow a LAN-based attacker to cause denial-of-service (DoS) conditions by downloading a crafted RAR compressed file onto a LAN-side host if the firewall has the “Anti-Malware” feature enabled.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

ATP100 Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

ATP100W Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-atp100w (same device)

ATP200 Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-atp200 (same device)

ATP500 Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-atp500 (same device)

ATP700 Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-atp700 (same device)

ATP800 Firmware · Zyxel

95%

4.32 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-atp800 (same device)

Usg Flex 100 Firmware · Zyxel

95%

4.50 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100 (same device)

Usg Flex 100AX Firmware · Zyxel

95%

4.50 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100ax (same device)

Usg Flex 100H Firmware · Zyxel

95%

4.50 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100h (same device)

Usg Flex 100W Firmware · Zyxel

95%

4.50 ≤ v < 5.375.37 5.37 patch1

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100w (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps-02-20-2024

References (1)

Vendor Advisory

Source: [email protected]

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps-02-20-2024

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUM[email protected]

Attack Vector: ADJACENT_NETWORK
Complexity: HIGH
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusANALYZED

CWE

CWE-476

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