Assessment
Why it matters
CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 99.9%; technical severity is CVSS 9.8.
A OS command injection vulnerability in the CGI program of Zyxel USG FLEX 100(W) firmware versions 5.00 through 5.21 Patch 1, USG FLEX 200 firmware versions 5.00 through 5.21 Patch 1, USG FLEX 500 firmware versions 5.00 through 5.21 Patch 1, USG FLEX 700 firmware versions 5.00 through 5.21 Patch 1, USG FLEX 50(W) firmware versions 5.10 through 5.21 Patch 1, USG20(W)-VPN firmware versions 5.10 through 5.21 Patch 1, ATP series firmware versions 5.10 through 5.21 Patch 1, VPN series firmware versions 4.60 through 5.21 Patch 1, which could allow an attacker to modify specific files and then execute some OS commands on a vulnerable device.
Who should care
- Teams operating Atp100 Firmware, Atp100w Firmware, Atp200 Firmware +14 more
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Atp100 Firmware, Atp100w Firmware, Atp200 Firmware +14 more is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- Apply updates per vendor instructions.
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Vendor remediation
Patch and remediation links
Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.
Technical details
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CWE
- CWE-78
- Affected versions
- Zyxel Atp100 Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Atp100w Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Atp200 Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Atp500 Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Atp700 Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Atp800 Firmware (Start Including: 5.10, End Excluding: 5.30); Zyxel Multiple Firewalls; Zyxel Usg Flex 100w Firmware (Start Including: 5.00, End Excluding: 5.30)
- Published
- 12 May 2022
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- CVE published
- Added to CISA KEV
- Latest EPSS score: 99.9%
- Signal calculated at 85