vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2023-34140

MEDIUM
6.5
CVSS Score
Published: July 17, 2023 at 05:49 PM UTC
Updated: June 17, 2026 at 06:02 AM UTC
50 products affected across 1 vendorUsg Flex 100W FirmwareUSG FLEX 200 firmwareUSG FLEX 700 firmware

Using ATP series firmware by Zyxel?

Get instant alerts when new vulnerabilities affect ATP series firmware - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
MEDIUM6.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

A buffer overflow vulnerability in the Zyxel ATP series firmware versions 4.32 through 5.36 Patch 2, USG FLEX series firmware versions 4.50 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 4.16 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 4.16 through 5.36 Patch 2, VPN series firmware versions 4.30 through 5.36 Patch 2, NXC2500 firmware versions 6.10(AAIG.0) through 6.10(AAIG.3), and NXC5500 firmware versions 6.10(AAOS.0) through 6.10(AAOS.4), could allow an unauthenticated, LAN-based attacker to cause denial of service (DoS) conditions by sending a crafted request to the CAPWAP daemon.

Affected

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

NXC2500 firmware· Zyxel
95%
v ≤ 6.106.10(aaig.0) ≤ v ≤ 6.10(aaig.3)
zyxel-nxc2500 (same device)
NXC5500 firmware· Zyxel
95%
v ≤ 6.106.10(aaos.0) ≤ v ≤ 6.10(aaos.4)
zyxel-nxc5500 (same device)
Usg 20W VPN Firmware· Zyxel
95%
4.16 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
Usg 2200-vpn Firmware· Zyxel
95%
4.30 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-2200-vpn (same device)
Usg Flex 100 Firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-flex-100 (same device)
Usg Flex 100W Firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-flex-100w (same device)
USG FLEX 200 firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-flex-200 (same device)
Usg Flex 50 Firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-flex-50 (same device)
USG FLEX 500 firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement
zyxel-usg-flex-500 (same device)
Usg Flex 50W Firmware· Zyxel
95%
4.50 ≤ v < 5.37
Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

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

Patch and advisory references

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-wlan-controllers

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

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

CVSS

6.5MEDIUMZyxel
Attack Vector
ADJACENT_NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-120

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card