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
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HZyxel Atp100
HWZyxelwszystkie wersjeZyxel Atp100 Firmware
OSZyxel4.35 – 4.35\(abps.3\)c0 (bez)Zyxel Atp200
HWZyxelwszystkie wersjeZyxel Atp200 Firmware
OSZyxel4.35 – 4.35\(abfw.3\)c0 (bez)Zyxel Atp500
HWZyxelwszystkie wersjeZyxel Atp500 Firmware
OSZyxel4.35 – 4.35\(abfu.3\)c0 (bez)Zyxel Atp800
HWZyxelwszystkie wersjeZyxel Atp800 Firmware
OSZyxel4.35 – 4.35\(abiq.3\)c0 (bez)Zyxel Nas326
HWZyxelwszystkie wersjeZyxel Nas326 Firmware
OSZyxel< 5.21\(aazf.7\)c0Zyxel Nas520
HWZyxelwszystkie wersjeZyxel Nas520 Firmware
OSZyxel< 5.21\(aasz.3\)c0Zyxel Nas540
HWZyxelwszystkie wersjeZyxel Nas540 Firmware
OSZyxel< 5.21\(aatb.4\)c0Zyxel Nas542
HWZyxelwszystkie wersjeZyxel Nas542 Firmware
OSZyxel< 5.21\(abag.4\)c0Zyxel Usg110
HWZyxelwszystkie wersjeZyxel Usg1100
HWZyxelwszystkie wersjeZyxel Usg1100 Firmware
OSZyxel4.35 – 4.35\(aapk.3\)c0 (bez)Zyxel Usg110 Firmware
OSZyxel4.35 – 4.35\(aaph.3\)c0 (bez)Zyxel Usg1900
HWZyxelwszystkie wersjeZyxel Usg1900 Firmware
OSZyxel4.35 – 4.35\(aapl.3\)c0 (bez)Zyxel Usg20 Vpn
HWZyxelwszystkie wersjeZyxel Usg20 Vpn Firmware
OSZyxel4.35 – 4.35\(abaq.3\)c0 (bez)Zyxel Usg20w Vpn
HWZyxelwszystkie wersjeZyxel Usg20w Vpn Firmware
OSZyxel4.35 – 4.35\(abar.3\)c0 (bez)Zyxel Usg210
HWZyxelwszystkie wersjeZyxel Usg210 Firmware
OSZyxel4.35 – 4.35\(aapi.3\)c0 (bez)Zyxel Usg2200
HWZyxelwszystkie wersjeZyxel Usg2200 Firmware
OSZyxel4.35 – 4.35\(abae.3\)c0 (bez)
CISA KEV — detailsi
- Vendori
- Zyxel
- Producti
- Multiple Network-Attached Storage (NAS) Devices
- Added to KEVi
- March 25, 2022
- Remediation deadline (US Federal)i
- April 15, 2022(overdue)
Apply updates per vendor instructions.
Multiple Zyxel network-attached storage (NAS) devices contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code.
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