OS command injection in Zyxel USG FLEX series firmware
Priority MEDIUM 41CWE-78Published · Updated
Key facts
- Attack vector
- Adjacent network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-78.
Summary
A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00759 55th 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
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Zyxel | USG FLEX series firmware | 4.50 through 5.36 Patch 2 | — | No fix listed | CNA |
| Zyxel | VPN series firmware | 4.20 through 5.36 Patch 2 | — | No fix listed | CNA |
- USG FLEX series firmware VendorZyxel Affected 4.50 through 5.36 Patch 2 Fixed in — No fix listed CNA
- VPN series firmware VendorZyxel Affected 4.20 through 5.36 Patch 2 Fixed in — No fix listed CNA
CPE configurations NVD · 30
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:zyxel:usg_2200-vpn_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_2200-vpn:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_200:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
- cpe:2.3:o:zyxel:usg_2200-vpn_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_2200-vpn:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_200:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
Show 20 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_500:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn100_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn2s_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn2s:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn300_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn300:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn50_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn50:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn_100_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn_100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn_300_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn_300:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:zywall_vpn_50_firmware:*:*:*:*:*:*:*:* | 4.20 to before 5.37 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:zywall_vpn_50:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
- cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_500:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn100_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn2s_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn2s:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn300_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn50_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn_100_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn_100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn_300_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn_300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:zywall_vpn_50_firmware:*:*:*:*:*:*:*:* Versions 4.20 to before 5.37 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:zywall_vpn_50:-:*:*:*:*:*:*:* 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 USG FLEX series firmware, VPN series firmware — zyxel.com/global/en/support/security-advisories/zyxel-secur…
5 records Highest priority Priority MEDIUM 2 MEDIUM, 3 LOW
Other records, highest priority first
- TI-2023-13277 OS command injection in Zyxel ATP series firmwarePriority MEDIUM 40
- TI-2023-16985 OS command injection in Zyxel ATP series firmwarePriority LOW 38
- TI-2023-16982 OS command injection in Zyxel ATP series firmwarePriority LOW 38
Timeline
- 2026-10-02 Threatist record created from CVE-2023-34139
- 2026-10-03 Alias added: GHSA-xjxm-x67w-v3c7
References
More Zyxel Usg 2200-vpn Firmware vulnerabilities
- TI-2023-16200 OS command injection in Zyxel ATP series firmware CVSS 3.1HIGH 8.8
- TI-2022-09869 Improper input validation in Zyxel USG/ZyWALL series firmware CVSS 3.1HIGH 7.8
- TI-2022-09870 OS command injection in Zyxel USG/ZyWALL series firmware CVSS 3.1HIGH 7.8
- TI-2023-16199 A format string vulnerability in the Zyxel ATP series firmware versions 5.10 through 5.36… CVSS 3.1HIGH 8.8
- TI-2023-13277 OS command injection in Zyxel ATP series firmware CVSS 3.1HIGH 8.8
- TI-2022-00646 Cross-site scripting in Zyxel USG/ZyWALL series firmware CVSS 3.1MEDIUM 6.1
Sources
- CVE-2023-34139 · CVE Program
- CVE-2023-34139 · NVD
- FIRST EPSS
- GHSA-xjxm-x67w-v3c7 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences