CVE-2011-3208: Buffer Overflow

A remotely exploitable buffer overflow flaw was found in Cyrus' nntpd. A malicious NNTP client would be able to exploit this to execute arbitrary code on a vulnerable nntpd server. If the 'allowanonymouslogin' option was set in imapd.conf, it could be done without authentication.

When compiled with FORTIFYSOURCE (the default on Red Hat Enterprise Linux 5 and 6, as well as Fedora), this flaw is not exploitable and will result in a crash of the nntpd service.

The following patch will correct the flaw:

diff --git a/imap/nntpd.c b/imap/nntpd.c index 56405d3..6b30174 100644 --- a/imap/nntpd.c +++ b/imap/nntpd.c @@ -4131,7 +4131,8 @@ static struct wildmat splitwildmats(char str) else if (c == '@') wild[n].not = -1; / absolute not (feeding) / else wild[n].not = 0;

- strcpy(p, wild[n].not ? c + 1 : c); + strncpy(p, wild[n].not ? c + 1 : c, pattern+sizeof(pattern) - p); + pattern[sizeof(pattern)-1] = '\0'; wild[n++].pat = xstrdup(pattern); } while (c != str); wild[n].pat = NULL;