Zyxel Warns Of Critical Vulnerabilities In Firewall And VPN Devices

Zyxel is warning customers of two critical-severity vulnerabilities in several of its firewall and VPN products. Unpatched, a threat actor could leverage the vulnerability without authentication. Here are the vulnerabilities:

CVE-2023-33009

A buffer overflow vulnerability in the notification function in some firewall versions could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device. 

CVE-2023-33010

A buffer overflow vulnerability in the ID processing function in some firewall versions could allow an unauthenticated attacker to cause DoS conditions and even a remote code execution on an affected device. 

Here’s a list of affected devices:

  • Zyxel ATP firmware versions ZLD V4.32 to V5.36 Patch 1 (fixed in ZLD V5.36 Patch 2)
  • Zyxel USG FLEX firmware versions ZLD V4.50 to V5.36 Patch 1 (fixed in ZLD V5.36 Patch 2)
  • Zyxel USG FLEX50(W) / USG20(W)-VPN firmware versions ZLD V4.25 to V5.36 Patch 1 (fixed in ZLD V5.36 Patch 2)
  • Zyxel VPN firmware versions ZLD V4.30 to V5.36 Patch 1 (fixed in ZLD V5.36 Patch 2)
  • Zyxel ZyWALL/USG firmware versions ZLD V4.25 to V4.73 Patch 1 (fixed in ZLD V4.73 Patch 2)

Zyxel has released patches for their firewalls. I’d strongly suggest installing them ASAP.

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