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).
Source: MITRE
Published: 2022-03-10
Updated: 2022-03-17
Type: CWE-436
Base Score: 6.9
Vector: AV:L/AC:M/Au:N/C:C/I:C/A:C
Impact Score: 10
Exploitability Score: 3.4
Severity: MEDIUM
Base Score: 8.4
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Impact Score: 5.9
Exploitability Score: 2.5
Severity: HIGH