From the screen-users mailing list:

    I've just released screen-4.0.3. This is not the promised next version
    with vertical split and other cool things, but just a security release
    that fixes two bugs in the utf8 combining characters handling. The
    bugs could be used to crash/hang screen by writing a special string
    to a window.

    The fixed version is (as usual) available via:

    ftp://ftp.uni-erlangen.de/pub/utilities/screen/screen-4.0.3.tar.gz

    Credits go to cstone & Rich Felker for finding the bugs.

Kees Cook of Ubuntu analysed this issue and determined that it's likely an
exploitable issue, but it's non trivial to exploit.  This will require a fair
amount of user interaction to exploit, thus the low severity.

This issue also likely affects RHEL2.1 and RHEL3