What is CVE-2020-9054?

CVE-2020-9054 is a critical-severity vulnerability in Zyxel Atp100, classified under OS Command Injection. CVSS score: 9.8/10. Published 2020-03-04.

How severe is CVE-2020-9054?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2020-9054 known to be exploited?

Yes. CVE-2020-9054 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-25), indicating it is being actively exploited. 18 public proof-of-concept repositories are indexed.

RCE in Zyxel Atp100

CVE-2020-9054

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 does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2

Vulnerability class: Command Injection (OS Command Injection)

EPSS: 1.000 (100.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

CWE-78 — OS Command Injection

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-03-25. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-04-15.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

cret@cert.org (Third Party Advisory, x_refsource_MISC)
cret@cert.org (x_refsource_CONFIRM, Vendor Advisory)
cret@cert.org (US Government Resource, x_refsource_CERT-VN, Third Party Advisory, third-party-advisory)
cret@cert.org (US Government Resource, Third Party Advisory, x_refsource_MISC)
cret@cert.org (Exploit, Third Party Advisory, x_refsource_MISC)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2020-9054?: CVE-2020-9054 is a critical-severity vulnerability in Zyxel Atp100, classified under OS Command Injection. CVSS score: 9.8/10. Published 2020-03-04.
How severe is CVE-2020-9054?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2020-9054 known to be exploited?: Yes. CVE-2020-9054 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-25), indicating it is being actively exploited. 18 public proof-of-concept repositories are indexed.