Out-of-Bounds Write in GNU Inetutils Telnet Daemon

telnetd in GNU inetutils through 2.7 allows an out-of-bounds write in the LINEMODE SLC (Set Local Characters) suboption handler because add_slc does not check whether the buffer is full.

telnetd in GNU Inetutils through 2.7 allows remote authentication bypass via a "-f root" value for the USER environment variable.

Information Disclosure via NEW_ENVIRON in GNU Inetutils Telnet

telnet in GNU inetutils through 2.7 allows servers to read arbitrary environment variables from clients via NEW_ENVIRON SEND USERVAR.

Privilege Escalation via Telnetd and Systemd Credentials

telnetd in GNU inetutils through 2.7 allows privilege escalation that can be exploited by abusing systemd service credentials support added to the login(1) implementation of util-linux in release 2.40. This is related to client control over the CREDENTIALS_DIRECTORY environment variable, and requires an unprivileged local user to create a login.noauth file.

Buffer overflow in the TFTP client in InetUtils 1.4.2 allows remote malicious DNS servers to execute arbitrary code via a large DNS response that is handled by the gethostbyname function.

Land IP denial of service.

FTP servers can allow an attacker to connect to arbitrary ports on machines other than the FTP client, aka FTP bounce.

Race condition in signal handling routine in ftpd, allowing read/write arbitrary files.

Denial of service of inetd on Linux through SYN and RST packets.

krb5: telnet client and server encrypt_keyid heap-based buffer overflow

Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.

GNU inetutils before 2.5 may allow privilege escalation because of unchecked return values of set*id() family functions in ftpd, rcp, rlogin, rsh, rshd, and uucpd. This is, for example, relevant if the setuid system call fails when a process is trying to drop privileges before letting an ordinary user control the activities of the process.

krb5-appl: NULL pointer dereference

telnetd in GNU Inetutils through 2.3, MIT krb5-appl through 1.0.3, and derivative works has a NULL pointer dereference via 0xff 0xf7 or 0xff 0xf8. In a typical installation, the telnetd application would crash but the telnet service would remain available through inetd. However, if the telnetd application has many crashes within a short time interval, the telnet service would become unavailable after inetd logs a "telnet/tcp server failing (looping), service terminated" error. NOTE: MIT krb5-appl is not supported upstream but is shipped by a few Linux distributions. The affected code was removed from the supported MIT Kerberos 5 (aka krb5) product many years ago, at version 1.8.

The ftp client in GNU Inetutils before 2.2 does not validate addresses returned by PASV/LSPV responses to make sure they match the server address. This is similar to CVE-2020-8284 for curl.