
The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Monday added two recently disclosed flaws in Zyxel firewalls to its Known Exploited Vulnerabilities (KEV) catalog, based on evidence of active exploitation.
The vulnerabilities, tracked as CVE-2023-33009 and CVE-2023-33010, are buffer overflow vulnerabilities that could allow an unauthenticated attacker to cause a denial of service (DoS) condition or remote code execution. .

A patch to close the security hole was released by Zyxel on May 24, 2023. The following list of devices are affected.
- ATP (versions ZLD V4.32 to V5.36 Patch 1, patched in ZLD V5.36 Patch 2)
- USG FLEX (versions ZLD V4.50 – V5.36 Patch 1, patched with ZLD V5.36 Patch 2)
- USG FLEX50(W) / USG20(W)-VPN (version ZLD V4.25 to V5.36 Patch 1, patched with ZLD V5.36 Patch 2)
- VPN (versions ZLD V4.30 – V5.36 Patch 1, patched with ZLD V5.36 Patch 2), and
- ZyWALL/USG (versions ZLD V4.25 – V4.73 Patch 1, patched with ZLD V4.73 Patch 2)
While the exact nature of the attack is unknown, this development comes just days after another Zyxel firewall flaw (CVE-2023-28771) was actively exploited to trap susceptible devices in the Mirai botnet. Done.
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Federal Civilian Executive (FCEB) agencies have until June 26, 2023 to remediate identified vulnerabilities to protect networks from potential threats.
In new guidance it issued last week, Zyxel advised customers to disable HTTP/HTTPS services from the WAN unless “absolutely” necessary, and disable UDP ports 500 and 4500 when not in use. calling to
This development fixes two flaws in GS1900 series switches (CVE-2022-45853) and 4G LTE and 5G NR outdoor routers (CVE-2023-27989) that could lead to escalation of privilege and denial of service for Taiwanese companies It was done at the same time as (DoS).