Skip to content
Fencer Vulns
medium 6.5

CVE-2023-6397 json

A null pointer dereference vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1 and USG FLEX series firmware…

published 2024-02-20 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-58634

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 22%
public exploits
0
none known

Summary

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.

Patch / fix

  • zyxel atp100_firmware 5.37
  • zyxel atp100w_firmware 5.37
  • zyxel atp200_firmware 5.37
  • zyxel atp500_firmware 5.37
  • zyxel atp700_firmware 5.37
  • zyxel atp800_firmware 5.37
  • zyxel usg_flex_100_firmware 5.37
  • zyxel usg_flex_100ax_firmware 5.37
  • zyxel usg_flex_100h_firmware 5.37
  • zyxel usg_flex_100w_firmware 5.37
  • zyxel usg_flex_200_firmware 5.37
  • zyxel usg_flex_200h_firmware 5.37
  • zyxel usg_flex_200hp_firmware 5.37
  • zyxel usg_flex_50_firmware 5.37
  • zyxel usg_flex_500_firmware 5.37
  • zyxel usg_flex_500h_firmware 5.37
  • zyxel usg_flex_50w_firmware 5.37
  • zyxel usg_flex_700_firmware 5.37
  • zyxel usg_flex_700h_firmware 5.37

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 22% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.3 CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Zyxel ATP series firmware
  • Zyxel USG FLEX series firmware

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.