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Zyxel Patches Critical Vulnerability in NAS Firmware

Networking solutions provider Zyxel has released patches for a critical-severity vulnerability impacting the firmware of multiple network attached storage (NAS) device models.

Networking solutions provider Zyxel has released patches for a critical-severity vulnerability impacting the firmware of multiple network attached storage (NAS) device models.

The security defect, tracked as CVE-2022-34747, carries a CVSS score of 9.8/10 and is publicly documented as a format string vulnerability impacting Zyxel NAS326 firmware versions prior to V5.21(AAZF.12)C0.

An attacker could exploit the vulnerability by sending specially crafted UDP packets to the affected products. Successful exploitation of the bug could allow an attacker to execute arbitrary code on the impacted device, the company said in an advisory.

“A format string vulnerability was found in a specific binary of Zyxel NAS products that could allow an attacker to achieve unauthorized remote code execution via a crafted UDP packet,” the company added.

[ READ: QNAP Warns of New ‘Deadbolt’ Ransomware Attacks Targeting NAS Users ]

Zyxel says its investigationhas identified only three NAS models that are affected and which are within their support lifetime.

The vendor silently patched the vulnerability in mid-August with firmware updates for NAS326, NAS540, and NAS542 device models, but delayed publication of the flaw details until this week.

Zyxel credited security researcher Shaposhnikov Ilya with reporting the vulnerability.

Zyxel’s advisory was published only days after QNAP warned of a new wave of Deadbolt ransomware attacks targeting its NAS users.

NAS devices – which are typically used for storing large amounts of data – are often targeted in ransomware attacks and remote code execution bugs in them could easily lead to complete device compromise.

Previously, Zyxel NAD products were targeted by a variant of the Mirai botnet, in attacks that exploited another critical-severity vulnerability leading to remote code execution.

Related: Details Released for Recently Patched Zyxel Firewall Vulns

Related: QNAP Warns of New ‘Deadbolt’ Ransomware Attacks Targeting NAS Users

Related: Zyxel Patches Zero-Day Flaw in Network Storage Products

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

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