The tag is present in Lintian version 2.104.319. That is the most recent version we know about.
The listed ELF binary appears to use a C library function that
performs DES encryption and/or decryption (
The DES block cipher can be broken by brute force on modern hardware,
which makes any use of these functions insecure. Also, programs that
use these functions cannot be linked against the
provided by glibc 2.28 and higher.
The program will need to be revised to use modern cryptographic
primitives and protocols. Depending on how the program uses these
functions, it may be necessary to continue using DES under some
circumstances (e.g. for protocol compatibility, or to retain the
ability to decrypt old data on disk) but this should be done using
the DES functions in a modern cryptographic library
This is almost certainly an upstream bug, and should be addressed
in coordination with the upstream maintainers of the software.
A false positive for this check is possible if the binary expects the
setkey_r to come from some shared library other than
libcrypt.so, and that shared library defines these
functions to do something other than perform DES encryption. If this
is the case it is appropriate to override this tag.