utility.c in telnetd in netkit telnet through 0.17 allows remote attackers to execute arbitrary code via short writes or urgent data, because of a buffer overflow involving the netclear and nextitem functions.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-10188
• https://appgateresearch.blogspot.com/2020/02/bravestarr-fedora-31-netkit-telnetd_28.html
• https://github.com/krb5/krb5-appl/blob/d00cd671dfe945791b33d4f1f6a5c57ae1667ef8/telnet/telnetd/utility.c#L205-L216
• https://lists.debian.org/debian-lts-announce/2020/05/msg00012.html
• https://lists.debian.org/debian-lts-announce/2020/08/msg00038.html
• https://lists.fedoraproject.org/archives/list/[email protected]/message/7FMTRRQTYKWZD2GMXX3GLZV46OLPCLVK/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/HLU6FL24BSQQEB2SJC26NLJ2MANQDA7M/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/K3VJ6V2Z3JRNJOBVHSOPMAC76PSSKG6A/
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-telnetd-EFJrEzPx
• https://www.arista.com/en/support/advisories-notices/security-advisories/10702-security-advisory-48
• https://www.oracle.com/security-alerts/cpuApr2021.html