CVE-2020-10188

A vulnerability was found where incorrect bounds checks in the telnet server’s (telnetd) handling of short writes and urgent data, could lead to information disclosure and corruption of heap data. An unauthenticated remote attacker could exploit these bugs by sending specially crafted telnet packets to achieve arbitrary code execution in the telnet server.

This vulnerability exists in the telnet-server package, not in the telnet client-side package. For a Red Hat Enterprise Linux host to be vulnerable, it must have telnet-server installed and the telnetd service enabled. Use of telnetd is not recommended, as it is an un-encrypted protocol with cleartext transmission of passwords; alternatives such as openssh are preferred.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

When in enforcing mode, SELinux as configured in Red Hat Enterprise Linux provides some mitigation against an exploit for telnet-server, because it limits the kind of operations it can perform and programs that can be run from the telnet-server's context.