CVE-2026-129117: C-Kermit 8.0.200 before 11.1.515 Missing Hostname Verification in AUTHENTICATION SSL
C-Kermit 8.0.200 before 11.1.515 contains an improper certificate validation vulnerability that allows machine-in-the-middle attackers to impersonate Telnet servers because sslreply() never calls sslcheckservername(). Attackers can refuse START-TLS, offer Telnet AUTHENTICATION SSL, and present any trusted CA certificate to capture user credentials and session data.
Affected Software
Event History
Frequently Asked Questions
Which connections are exposed to this issue?
Telnet connections using C-Kermit AUTHENTICATION SSL are exposed when a network attacker can position themselves between the client and the intended server. The attacker can refuse START-TLS and then offer AUTHENTICATION SSL.
What does an attacker need to successfully impersonate a server?
The attacker needs a machine-in-the-middle position and a certificate trusted by the client from any trusted certificate authority. Because the hostname is not checked, the certificate does not need to match the intended Telnet server.
What can be compromised if exploitation succeeds?
An attacker can capture user credentials and session data. The stated impact includes high confidentiality and integrity impact.
What versions should be remediated?
C-Kermit versions from 8.0.200 before 11.1.515 are affected. Update to version 11.1.515 or later.