Vulnerability Monitor

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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

Published

2020-03-04T20:15:10.750

Last Modified

2025-03-21T19:50:32.680

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 9.8 (CRITICAL)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:C/I:C/A:C

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: COMPLETE
  • Integrity Impact: COMPLETE
  • Availability Impact: COMPLETE
Exploitability Score

10.0

Impact Score

10.0

Weaknesses
  • Type: Secondary
    CWE-78
  • Type: Primary
    CWE-78
  • Type: Secondary
    CWE-78
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System zyxel nas326_firmware < 5.21\(aazf.7\)c0 Yes
Hardware zyxel nas326 - No
Operating System zyxel nas520_firmware < 5.21\(aasz.3\)c0 Yes
Hardware zyxel nas520 - No
Operating System zyxel nas540_firmware < 5.21\(aatb.4\)c0 Yes
Hardware zyxel nas540 - No
Operating System zyxel nas542_firmware < 5.21\(abag.4\)c0 Yes
Hardware zyxel nas542 - No
Operating System zyxel atp100_firmware < 4.35\(abps.3\)c0 Yes
Hardware zyxel atp100 - No
Operating System zyxel atp200_firmware < 4.35\(abfw.3\)c0 Yes
Hardware zyxel atp200 - No
Operating System zyxel atp500_firmware < 4.35\(abfu.3\)c0 Yes
Hardware zyxel atp500 - No
Operating System zyxel atp800_firmware < 4.35\(abiq.3\)c0 Yes
Hardware zyxel atp800 - No
Operating System zyxel usg20-vpn_firmware < 4.35\(abaq.3\)c0 Yes
Hardware zyxel usg20-vpn - No
Operating System zyxel usg20w-vpn_firmware < 4.35\(abar.3\)c0 Yes
Hardware zyxel usg20w-vpn - No
Operating System zyxel usg40_firmware < 4.35\(aala.3\)c0 Yes
Hardware zyxel usg40 - No
Operating System zyxel usg40w_firmware < 4.35\(aalb.3\)c0 Yes
Hardware zyxel usg40w - No
Operating System zyxel usg60_firmware < 4.35\(aaky.3\)c0 Yes
Hardware zyxel usg60 - No
Operating System zyxel usg60w_firmware < 4.35\(aakz.3\)c0 Yes
Hardware zyxel usg60w - No
Operating System zyxel usg110_firmware < 4.35\(aaph.3\)c0 Yes
Hardware zyxel usg110 - No
Operating System zyxel usg210_firmware < 4.35\(aapi.3\)c0 Yes
Hardware zyxel usg210 - No
Operating System zyxel usg310_firmware < 4.35\(aapj.3\)c0 Yes
Hardware zyxel usg310 - No
Operating System zyxel usg1100_firmware < 4.35\(aapk.3\)c0 Yes
Hardware zyxel usg1100 - No
Operating System zyxel usg1900_firmware < 4.35\(aapl.3\)c0 Yes
Hardware zyxel usg1900 - No
Operating System zyxel usg2200_firmware < 4.35\(abae.3\)c0 Yes
Hardware zyxel usg2200 - No
Operating System zyxel vpn50_firmware < 4.35\(abhl.3\)c0 Yes
Hardware zyxel vpn50 - No
Operating System zyxel vpn100_firmware < 4.35\(abfv.3\)c0 Yes
Hardware zyxel vpn100 - No
Operating System zyxel vpn300_firmware < 4.35\(abfc.3\)c0 Yes
Hardware zyxel vpn300 - No
Operating System zyxel vpn1000_firmware < 4.35\(abip.3\)c0 Yes
Hardware zyxel vpn1000 - No
Operating System zyxel zywall110_firmware < 4.35\(aaaa.3\)c0 Yes
Hardware zyxel zywall110 - No
Operating System zyxel zywall310_firmware < 4.35\(aaab.3\)c0 Yes
Hardware zyxel zywall310 - No
Operating System zyxel zywall1100_firmware < 4.35\(aaac.3\)c0 Yes
Hardware zyxel zywall1100 - No
References