Skip to page content

AEGLIX MIND

Intelligence for Africa and the Gulf

AEGLIX vulnerability intelligence

CVE-2020-9054

CRITICAL · CVSS 9.8 · Analyzed

Published: 2020-03-04 · Updated: 2026-10-08 · Source: NVD

Vulnerability overview

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

Severity and scoring

CVSS score
9.8 · CRITICAL
CVSS version
3.1
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weaknesses
CWE-78

CVSS measures technical severity; it does not establish whether this vulnerability is being exploited in your environment.

Known exploitation and remediation

Listed in CISA’s Known Exploited Vulnerabilities catalog.

Affected product
Zyxel · Multiple Network-Attached Storage (NAS) Devices
Added to catalog
2022-03-25
Required action
Apply updates per vendor instructions.
CISA remediation due date
2022-04-15

CISA deadlines apply to the organizations covered by its directives. Confirm your own remediation requirements.

Verify affected versions and patch availability in the vendor advisory before making changes.

Affected products and versions

  • cpe:2.3:o:zyxel:nas326_firmware:*:*:*:*:*:*:*:*

    Before (exclusive): 5.21\(aazf.10\)c0

  • cpe:2.3:o:zyxel:nas520_firmware:*:*:*:*:*:*:*:*

    Before (exclusive): 5.21\(aasz.3\)c0

  • cpe:2.3:o:zyxel:nas540_firmware:*:*:*:*:*:*:*:*

    Before (exclusive): 5.21\(aatb.7\)c0

  • cpe:2.3:o:zyxel:nas542_firmware:*:*:*:*:*:*:*:*

    Before (exclusive): 5.21\(abag.7\)c0

  • cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abps.3\)c0

  • cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abfw.3\)c0

  • cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abfu.3\)c0

  • cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abiq.3\)c0

  • cpe:2.3:o:zyxel:usg20-vpn_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abaq.3\)c0

  • cpe:2.3:o:zyxel:usg20w-vpn_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abar.3\)c0

  • cpe:2.3:o:zyxel:usg40_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aala.3\)c0

  • cpe:2.3:o:zyxel:usg40w_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aalb.3\)c0

  • cpe:2.3:o:zyxel:usg60_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aaky.3\)c0

  • cpe:2.3:o:zyxel:usg60w_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aakz.3\)c0

  • cpe:2.3:o:zyxel:usg110_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aaph.3\)c0

  • cpe:2.3:o:zyxel:usg210_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aapi.3\)c0

  • cpe:2.3:o:zyxel:usg310_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aapj.3\)c0

  • cpe:2.3:o:zyxel:usg1100_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aapk.3\)c0

  • cpe:2.3:o:zyxel:usg1900_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aapl.3\)c0

  • cpe:2.3:o:zyxel:usg2200_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abae.3\)c0

  • cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abhl.3\)c0

  • cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abfv.3\)c0

  • cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abfc.3\)c0

  • cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(abip.3\)c0

  • cpe:2.3:o:zyxel:zywall110_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aaaa.3\)c0

  • cpe:2.3:o:zyxel:zywall310_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aaab.3\)c0

  • cpe:2.3:o:zyxel:zywall1100_firmware:*:*:*:*:*:*:*:*

    From (inclusive): 4.35

    Before (exclusive): 4.35\(aaac.3\)c0

These are NVD CPE applicability entries. Some products depend on configuration conditions; consult the official record to confirm applicability.

Advisories and references

Explore official sources

Read the official NVD record ↗

Explore the CISA catalog ↗

Back to CVE intelligence