package/mutt: fix CVE-2020-28896

Mutt before 2.0.2 and NeoMutt before 2020-11-20 did not ensure that
$ssl_force_tls was processed if an IMAP server's initial server response
was invalid. The connection was not properly closed, and the code could
continue attempting to authenticate. This could result in authentication
credentials being exposed on an unencrypted connection, or to a
machine-in-the-middle.

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mutt/0001-Ensure-IMAP-connection-is-closed-after-a-connection-error.patch

@@ -0,0 +1,48 @@
+From 04b06aaa3e0cc0022b9b01dbca2863756ebbf59a Mon Sep 17 00:00:00 2001
+From: Kevin McCarthy <kevin@8t8.us>
+Date: Mon, 16 Nov 2020 10:20:21 -0800
+Subject: [PATCH] Ensure IMAP connection is closed after a connection error.
+
+During connection, if the server provided an illegal initial response,
+Mutt "bailed", but did not actually close the connection.  The calling
+code unfortunately relied on the connection status to decide to
+continue with authentication, instead of checking the "bail" return
+value.
+
+This could result in authentication credentials being sent over an
+unencrypted connection, without $ssl_force_tls being consulted.
+
+Fix this by strictly closing the connection on any invalid response
+during connection.  The fix is intentionally small, to ease
+backporting.  A better fix would include removing the 'err_close_conn'
+label, and perhaps adding return value checking in the caller (though
+this change obviates the need for that).
+
+This addresses CVE-2020-28896.  Thanks to Gabriel Salles-Loustau for
+reporting the problem, and providing test cases to reproduce.
+
+[Retrieved from:
+https://gitlab.com/muttmua/mutt/-/commit/04b06aaa3e0cc0022b9b01dbca2863756ebbf59a]
+Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+---
+ imap/imap.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/imap/imap.c b/imap/imap.c
+index b24e8a3f..b13dd54d 100644
+--- a/imap/imap.c
++++ b/imap/imap.c
+@@ -561,9 +561,9 @@ int imap_open_connection (IMAP_DATA* idata)
+ 
+ #if defined(USE_SSL)
+ err_close_conn:
+-  imap_close_connection (idata);
+ #endif
+ bail:
++  imap_close_connection (idata);
+   FREE (&idata->capstr);
+   return -1;
+ }
+-- 
+GitLab
+

package/mutt/mutt.mk

@@ -11,6 +11,9 @@ MUTT_LICENSE_FILES = GPL
 MUTT_DEPENDENCIES = ncurses
 MUTT_CONF_OPTS = --disable-doc --disable-smtp
 
+# 0001-Ensure-IMAP-connection-is-closed-after-a-connection-error.patch
+MUTT_IGNORE_CVES += CVE-2020-28896
+
 ifeq ($(BR2_PACKAGE_LIBICONV),y)
 MUTT_DEPENDENCIES += libiconv
 MUTT_CONF_OPTS += --enable-iconv