CVE-2005-2040

Vulnerability

Multiple buffer overflow vulnerabilities exist in the getterminaltype function of the telnetd server in Heimdal versions prior to 0.6.5. These overflows can be triggered when processing terminal type information during telnet negotiations. The vulnerable code path is reachable without authentication, as telnetd typically accepts connections from any remote host. [2][3]

Exploitation

An attacker can exploit these vulnerabilities by connecting to the telnetd service and sending a specially crafted terminal type string. No authentication is required, and the attacker only needs network access to the telnet port (usually TCP 23). The crafted input causes a buffer overflow, potentially leading to code execution. [2][3]

Impact

Successful exploitation allows remote attackers to execute arbitrary code with the privileges of the telnetd process, typically root. This results in full compromise of the affected system, including unauthorized access, data disclosure, and potential further propagation. [2][3]

Mitigation

The vulnerabilities are fixed in Heimdal version 0.6.5 and later. Users should upgrade to the latest version. For example, Gentoo users should emerge >=app-crypt/heimdal-0.6.5. [3] No workarounds are available. [3]