Read the docs
TI-2023-04062 Aliases CVE-2023-4398GHSA-rfqw-q592-fp2h

Integer overflow in Zyxel ATP series firmware

Priority MEDIUM 41CWE-190Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
No fix listed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-190 and the CVSS impact.

Summary

An integer overflow vulnerability in the source code of the QuickSec IPSec toolkit used in the VPN feature of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions on an affected device by sending a crafted IKE packet.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00881 59th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ZyxelATP series firmwareversions 4.32 through 5.37—No fix listedCNA
ZyxelUSG FLEX series firmwareversions 4.50 through 5.37—No fix listedCNA
ZyxelUSG FLEX 50(W) series firmwareversions 4.16 through 5.37—No fix listedCNA
ZyxelUSG20(W)-VPN series firmwareversions 4.16 through 5.37—No fix listedCNA
ZyxelVPN series firmwareversions 4.30 through 5.37—No fix listedCNA
  • ATP series firmware VendorZyxel Affected versions 4.32 through 5.37 Fixed in — No fix listed CNA
  • USG FLEX series firmware VendorZyxel Affected versions 4.50 through 5.37 Fixed in — No fix listed CNA
  • USG FLEX 50(W) series firmware VendorZyxel Affected versions 4.16 through 5.37 Fixed in — No fix listed CNA
  • USG20(W)-VPN series firmware VendorZyxel Affected versions 4.16 through 5.37 Fixed in — No fix listed CNA
  • VPN series firmware VendorZyxel Affected versions 4.30 through 5.37 Fixed in — No fix listed CNA

CPE configurations NVD · 23

CPEVersionsRoleVendor
cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:*4.32 – 5.37VulnerableZyxel
cpe:2.3:h:zyxel:atp100:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:atp100w:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:atp200:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:atp500:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:atp700:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:atp800:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:*4.50 – 5.37VulnerableZyxel
cpe:2.3:h:zyxel:usg_flex_100:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
  • cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:* Versions 4.32 – 5.37 Vulnerable ·Zyxel
  • cpe:2.3:h:zyxel:atp100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:atp100w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:atp200:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:atp500:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:atp700:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:atp800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:* Versions 4.50 – 5.37 Vulnerable ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
Show 13 more CPE
CPEVersionsRoleVendor
cpe:2.3:h:zyxel:usg_flex_200:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:usg_flex_500:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:*4.16 – 5.37VulnerableZyxel
cpe:2.3:h:zyxel:usg_20w-vpn:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:vpn50w:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:*4.30 – 5.37VulnerableZyxel
cpe:2.3:h:zyxel:vpn100:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:vpn1000:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:vpn300:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
cpe:2.3:h:zyxel:vpn50:-:*:*:*:*:*:*:*not specified by NVDRunning onZyxel
  • cpe:2.3:h:zyxel:usg_flex_200:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_500:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:* Versions 4.16 – 5.37 Vulnerable ·Zyxel
  • cpe:2.3:h:zyxel:usg_20w-vpn:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:vpn50w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:o:zyxel:zld:*:*:*:*:*:*:*:* Versions 4.30 – 5.37 Vulnerable ·Zyxel
  • cpe:2.3:h:zyxel:vpn100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:vpn1000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:vpn300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
  • cpe:2.3:h:zyxel:vpn50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel

Remediation

No fixed version listed by the sources yet.

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Zyxel ATP series firmware, USG FLEX 50(W) series firmware and 3 more products — zyxel.com/global/en/support/security-advisories/zyxel-secur…

    9 records Highest priority Priority MEDIUM 1 MEDIUM, 8 LOW

    Other records, highest priority first

    • TI-2023-17585 Cross-site scripting in Zyxel ATP series firmwarePriority LOW 28
    • TI-2023-19359 Buffer overflow in Zyxel ATP series firmwarePriority LOW 24
    • TI-2023-19358 Improper privilege management in Zyxel ATP series firmwarePriority LOW 24
    Show all 9 records → Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2023-4398
  2. 2026-10-03 Alias added: GHSA-rfqw-q592-fp2h

References

Advisory 1

  • TI-2024-10813 Path traversal in Zyxel ATP series firmware KEVCVSS 3.1CRITICAL 9.8
  • TI-2020-15281 A stack-based buffer overflow in fbwifi_continue.cgi on Zyxel UTM and VPN series of… CVSS 3.1CRITICAL 9.8
  • TI-2025-08373 Missing authorization in Zyxel ATP series firmware CVSS 3.1HIGH 8.1
  • TI-2024-28064 NULL pointer dereference in Zyxel ATP series firmware CVSS 3.1HIGH 7.5
  • TI-2024-28063 OS command injection in Zyxel ATP series firmware CVSS 3.1HIGH 8.1
  • TI-2025-07391 OS command injection in Zyxel ATP series firmware CVSS 3.1HIGH 7.2
See all 20 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences