+++ This bug was initially created as a clone of Bug #750929 +++

Description of problem:
I have set

set folder=imaps://matej.cz/INBOX

and when starting mutt, I get this crash:

Program received signal SIGSEGV, Segmentation fault.
__strstr_sse2 (haystack_start=0x1 <Address 0x1 out of bounds>, 
    needle_start=0x4a8248 "-----BEGIN") at ../string/strstr.c:63
63	  while (*haystack && *needle)
Missing separate debuginfos, use: debuginfo-install bzip2-libs-1.0.5-7.el6_0.x86_64 keyutils-libs-1.4-3.el6.x86_64 libgcrypt-1.4.5-9.el6.x86_64 libgpg-error-1.7-4.el6.x86_64 libtasn1-2.3-3.el6.x86_64 nss-softokn-freebl-3.12.9-10.el6.x86_64 zlib-1.2.3-27.el6.x86_64
(gdb) thread apply all backtrace

Thread 1 (Thread 0x7ffff7fd67c0 (LWP 24792)):
#0  __strstr_sse2 (haystack_start=0x1 <Address 0x1 out of bounds>, 
    needle_start=0x4a8248 "-----BEGIN") at ../string/strstr.c:63
#1  0x000000000048798b in tls_compare_certificates (certdata=0xb9b8f0, certstat=0, 
    hostname=<value optimized out>, chainidx=0, certerr=0x7fffffffca18, savedcert=0x7fffffffca14)
    at mutt_ssl_gnutls.c:438
#2  tls_check_preauth (certdata=0xb9b8f0, certstat=0, hostname=<value optimized out>, 
    chainidx=0, certerr=0x7fffffffca18, savedcert=0x7fffffffca14) at mutt_ssl_gnutls.c:590
#3  0x0000000000489131 in tls_check_certificate (conn=0xb7d950) at mutt_ssl_gnutls.c:1005
#4  tls_negotiate (conn=0xb7d950) at mutt_ssl_gnutls.c:346
#5  0x000000000048950c in tls_socket_open (conn=0xb7d950) at mutt_ssl_gnutls.c:162
#6  0x0000000000490a27 in imap_open_connection (idata=0xb7def0) at imap.c:407
#7  0x0000000000490d68 in imap_conn_find (account=0x7fffffffd860, flags=<value optimized out>)
    at imap.c:371
#8  0x00000000004924af in imap_open_mailbox (ctx=0xb7c650) at imap.c:574
#9  0x0000000000443be5 in mx_open_mailbox (path=<value optimized out>, flags=0, pctx=0x0)
    at mx.c:661
#10 0x0000000000439aa6 in main (argc=1, argv=<value optimized out>) at main.c:1017
(gdb) 

Version-Release number of selected component (if applicable):
mutt-1.5.20-2.20091214hg736b6a.el6_1.1.x86_64

How reproducible:
100% (three out of three attempts, also with attempt to access POP3 account)

Steps to Reproduce:
1.try to access IMAP or POP3 account
2.
3.
  
Actual results:
crash

Expected results:
opened mailbox

Additional info:

--- Additional comment from hhorak on 2011-11-03 11:29:31 EDT ---

Created attachment 531585 [details]
proposed patch to parse certificates file securely

I've managed to reproduce the failure, using a little bit damaged certificate file (added a zero byte to the beginning). mutt seems not to be robust enough when working with certificates file.