When I attach a message from mailbox (shift+a in send window, select
folder, tag messages and "q" ... oops) mutt (often) crashes:
segmentation fault (core dumped)  mutt
$ gdb mutt core
...
#0  0x40275c34 in __libc_realloc (oldmem=0x40316688, bytes=161)
---Type <return> to continue, or q <return> to quit---
    at malloc.c:3289
3289    malloc.c: No such file or directory.
        in malloc.c

% rpm -q mutt glibc slang
mutt-1.2.5i-6
glibc-2.2.1-3
slang-1.4.2-1

With RH7.0 it never happend but with RH7.1b and Rawhide it happens.