CVE-2022-25219: Phicomm k2 Firmware

High severity, CVSS 8.4. EPSS: 0.8% chance of exploitation in the next 30 days.

A null byte interaction error has been discovered in the code that the telnetd_startup daemon uses to construct a pair of ephemeral passwords that allow a user to spawn a telnet service on the router, and to ensure that the telnet service persists upon reboot. By means of a crafted exchange of UDP packets, an unauthenticated attacker on the local network can leverage this null byte interaction error in such a way as to make those ephemeral passwords predictable (with 1-in-94 odds). Since the attacker must manipulate data processed by the OpenSSL function RSA_public_decrypt(), successful exploitation of this vulnerability depends on the use of an unpadded RSA cipher (CVE-2022-25218).

Affected products

• Phicomm k2 Firmware: up to and including 22.5.9.163
• Phicomm k2g Firmware: up to and including 22.6.3.20
• Phicomm k2p Firmware: up to and including 20.4.1.7
• Phicomm k3 Firmware: up to and including 21.5.37.246
• Phicomm k3c Firmware: up to and including 32.1.15.93

Published 2022-03-10. Last modified 2026-06-17.