CVE-2023-33010
Zyxel Multiple Firewalls Buffer Overflow Vulnerability
Zyxel Multiple Firewalls
A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.
Exploitation status
CISA Known Exploited Vulnerabilities
Listed by CISA on 5 June 2023. US federal agencies were required to remediate it by 26 June 2023.
EPSS — exploitation probability
FIRST puts the probability of exploitation activity in the next 30 days at 29%, which is higher than 98.2% of all scored vulnerabilities. EPSS is a forecast of activity, not a measure of severity, and it is rescored daily.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Frequently asked questions
Is CVE-2023-33010 being exploited by ransomware groups?
No ransomware group in this database is currently recorded as exploiting CVE-2023-33010.
What does CVE-2023-33010 affect?
CVE-2023-33010 affects Zyxel Multiple Firewalls. A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.
How severe is CVE-2023-33010?
CVE-2023-33010 is rated CRITICAL with a CVSS base score of 9.8. EPSS puts the probability of exploitation in the next 30 days at 29%, higher than 98.2% of all scored vulnerabilities. It is listed in the CISA Known Exploited Vulnerabilities catalog, with a federal remediation deadline of 26 June 2023.
How should organisations respond to CVE-2023-33010?
Apply the vendor patch for Zyxel Multiple Firewalls as the first priority, and treat any internet-facing instance as the most urgent. Because this vulnerability is associated with ransomware activity, also review whether the affected systems were reachable before patching, rather than assuming that patching alone closes the incident.