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

• Zyxel Atp100

  HW
  Zyxel
  all versions

• Zyxel Atp100 Firmware

  OS
  Zyxel
  4.35 – 4.35\(abps.3\)c0 (excl.)

• Zyxel Atp200

  HW
  Zyxel
  all versions

• Zyxel Atp200 Firmware

  OS
  Zyxel
  4.35 – 4.35\(abfw.3\)c0 (excl.)

• Zyxel Atp500

  HW
  Zyxel
  all versions

• Zyxel Atp500 Firmware

  OS
  Zyxel
  4.35 – 4.35\(abfu.3\)c0 (excl.)

• Zyxel Atp800

  HW
  Zyxel
  all versions

• Zyxel Atp800 Firmware

  OS
  Zyxel
  4.35 – 4.35\(abiq.3\)c0 (excl.)

• Zyxel Nas326

  HW
  Zyxel
  all versions

• Zyxel Nas326 Firmware

  OS
  Zyxel
  < 5.21\(aazf.7\)c0

• Zyxel Nas520

  HW
  Zyxel
  all versions

• Zyxel Nas520 Firmware

  OS
  Zyxel
  < 5.21\(aasz.3\)c0

• Zyxel Nas540

  HW
  Zyxel
  all versions

• Zyxel Nas540 Firmware

  OS
  Zyxel
  < 5.21\(aatb.4\)c0

• Zyxel Nas542

  HW
  Zyxel
  all versions

• Zyxel Nas542 Firmware

  OS
  Zyxel
  < 5.21\(abag.4\)c0

• Zyxel Usg110

  HW
  Zyxel
  all versions

• Zyxel Usg1100

  HW
  Zyxel
  all versions

• Zyxel Usg1100 Firmware

  OS
  Zyxel
  4.35 – 4.35\(aapk.3\)c0 (excl.)

• Zyxel Usg110 Firmware

  OS
  Zyxel
  4.35 – 4.35\(aaph.3\)c0 (excl.)

• Zyxel Usg1900

  HW
  Zyxel
  all versions

• Zyxel Usg1900 Firmware

  OS
  Zyxel
  4.35 – 4.35\(aapl.3\)c0 (excl.)

• Zyxel Usg20 Vpn

  HW
  Zyxel
  all versions

• Zyxel Usg20 Vpn Firmware

  OS
  Zyxel
  4.35 – 4.35\(abaq.3\)c0 (excl.)

• Zyxel Usg20w Vpn

  HW
  Zyxel
  all versions

• Zyxel Usg20w Vpn Firmware

  OS
  Zyxel
  4.35 – 4.35\(abar.3\)c0 (excl.)

• Zyxel Usg210

  HW
  Zyxel
  all versions

• Zyxel Usg210 Firmware

  OS
  Zyxel
  4.35 – 4.35\(aapi.3\)c0 (excl.)

• Zyxel Usg2200

  HW
  Zyxel
  all versions

• Zyxel Usg2200 Firmware

  OS
  Zyxel
  4.35 – 4.35\(abae.3\)c0 (excl.)