OS command injection in Zyxel ATP series firmware
Priority MEDIUM 43CWE-78Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- 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
The post-authentication command injection vulnerability in the CLI command of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.16 through 5.35, USG20(W)-VPN firmware versions 4.16 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow an authenticated attacker to execute some OS commands remotely.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01453 73rd 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 | ATP series firmware | 4.32 through 5.35 | — | No fix listed | CNA |
| Zyxel | USG FLEX series firmware | 4.50 through 5.35 | — | No fix listed | CNA |
| Zyxel | USG FLEX 50(W) firmware | 4.16 through 5.35 | — | No fix listed | CNA |
| Zyxel | USG20(W)-VPN firmware | 4.16 through 5.35 | — | No fix listed | CNA |
| Zyxel | VPN series firmware | 4.30 through 5.35 | — | No fix listed | CNA |
- ATP series firmware VendorZyxel Affected 4.32 through 5.35 Fixed in — No fix listed CNA
- USG FLEX series firmware VendorZyxel Affected 4.50 through 5.35 Fixed in — No fix listed CNA
- USG FLEX 50(W) firmware VendorZyxel Affected 4.16 through 5.35 Fixed in — No fix listed CNA
- USG20(W)-VPN firmware VendorZyxel Affected 4.16 through 5.35 Fixed in — No fix listed CNA
- VPN series firmware VendorZyxel Affected 4.30 through 5.35 Fixed in — No fix listed CNA
CPE configurations NVD · 38
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp200:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:atp700_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp700:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp500:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:atp100w_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp100w:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
- cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp200:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:atp700_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp700:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp500:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:atp100w_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp100w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
Show 28 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:* | 4.32 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:atp800:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_200:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_500:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:* | 4.50 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_20w-vpn_firmware:*:*:*:*:*:*:*:* | 4.16 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_20w-vpn:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:* | 4.16 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:usg20-vpn_firmware:*:*:*:*:*:*:*:* | 4.30 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:usg20-vpn:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:* | 4.30 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:vpn100:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:* | 4.30 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:vpn1000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:* | 4.30 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:vpn300:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
| cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:* | 4.30 to before 5.36 | Vulnerable | Zyxel |
| cpe:2.3:h:zyxel:vpn50:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Zyxel |
- cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:* Versions 4.32 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:atp800:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 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_50_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 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_500_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 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_700_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_700:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:* Versions 4.50 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_100w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_20w-vpn_firmware:*:*:*:*:*:*:*:* Versions 4.16 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_20w-vpn:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:* Versions 4.16 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg_flex_50w:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:usg20-vpn_firmware:*:*:*:*:*:*:*:* Versions 4.30 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:usg20-vpn:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:* Versions 4.30 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:vpn100:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:* Versions 4.30 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:vpn1000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:* Versions 4.30 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:vpn300:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
- cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:* Versions 4.30 to before 5.36 Vulnerable ·Zyxel
- cpe:2.3:h:zyxel:vpn50:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Zyxel
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2023-27991
- 2026-10-03 Alias added: GHSA-2j4f-52m8-xq9h
References
More Zyxel Atp100 Firmware vulnerabilities
- TI-2023-16198 Buffer overflow in Zyxel ATP series firmware KEVCVSS 3.1CRITICAL 9.8
- TI-2023-16197 Buffer overflow in Zyxel ATP series firmware KEVCVSS 3.1CRITICAL 9.8
- TI-2023-13281 OS command injection in Zyxel ZyWALL/USG series firmware KEVCVSS 3.1CRITICAL 9.8
- TI-2022-12682 OS command injection in Zyxel USG FLEX 100 firmware KEVCVSS 3.1CRITICAL 9.8
- TI-2020-17772 Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with… KEVCVSS 3.1CRITICAL 9.8
- TI-2020-07267 OS command injection in Zyxel NAS326 KEVCVSS 3.1CRITICAL 9.8
Sources
- CVE-2023-27991 · CVE Program
- CVE-2023-27991 · NVD
- FIRST EPSS
- GHSA-2j4f-52m8-xq9h · 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