CVE-2020-9054
CWE-78
103.8
RPSRPS range: 0–105; KEV-listed vulnerabilities can receive an exploitation amplifier.
Description
Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker do…
Source: NVD
Signals
- CVSS
- 9.8
- Critical · v3.1
- EPSS
- 99.98%
- Probability of exploitation in the next 30 days (FIRST)
- CISA KEV
- In CISA KEV since Mar 2022
- Fix commit
- No known fix commit
- Sources: MoreFixes, FreshFixes
- Weakness
- CWE-78
- Published
- 4 Mar 2020
- Last modified 10 Nov 2025
How to read these signals: RPS · EPSS · CISA KEV · Data sources
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Data as of 7 Oct 2026, 05:16 UK time