The write_one_header function in mutt 1.5.23 does not properly handle newline characters at the beginning of a header, which allows remote attackers to cause a denial of service (crash) via a header with an empty body, which triggers a heap-based buffer overflow in the mutt_substrdup function.

Buffer overflow in copy.c in Mutt before 1.5.23 allows remote attackers to cause a denial of service (crash) via a crafted RFC2047 header line, related to address expansion.

mutt_ssl.c in mutt 1.5.19 and 1.5.20, when OpenSSL is used, does not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.

Mutt 1.5.19, when linked against (1) OpenSSL (mutt_ssl.c) or (2) GnuTLS (mutt_ssl_gnutls.c), allows connections when only one TLS certificate in the chain is accepted instead of verifying the entire chain, which allows remote attackers to spoof trusted servers via a man-in-the-middle attack.

Race condition in the safe_open function in the Mutt mail client 1.5.12 and earlier, when creating temporary files in an NFS filesystem, allows local users to overwrite arbitrary files due to limitations of the use of the O_EXCL flag on NFS filesystems.

The mutt_adv_mktemp function in the Mutt mail client 1.5.12 and earlier does not properly verify that temporary files have been created with restricted permissions, which might allow local users to create files with weak permissions via a race condition between the mktemp and safe_fopen function calls.

Buffer overflow in the mutt_decode_xbit function in Handler.c for Mutt 1.5.10 allows remote attackers to execute arbitrary code, possibly due to interactions with libiconv or gettext.

Buffer overflow in Mutt 1.4.0 and possibly earlier versions, 1.5.x up to 1.5.3, and other programs that use Mutt code such as Balsa before 2.0.10, allows a remote malicious IMAP server to cause a denial of service (crash) and possibly execute arbitrary code via a crafted folder.