From b82c3ccb65e3279996a690ebf577263d7730e0b3 Mon Sep 17 00:00:00 2001 From: Matthias Andree Date: Thu, 26 Aug 2021 23:53:14 +0200 Subject: SECURITY: IMAP: PREAUTH->abort if STARTTLS needed On --sslproto auto (or other nonempty values), when receiving IMAP PREAUTH state, abort the connection, rather than continuing with cleartext. --ssl is unaffected because it always negotiates TLS. See fetchmail-SA-2021-02.txt for details. --- NEWS | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'NEWS') diff --git a/NEWS b/NEWS index 2add2b6a..2d51b6e7 100644 --- a/NEWS +++ b/NEWS @@ -81,6 +81,23 @@ removed from a 6.5.0 or newer release.) messages. This will not be fixed, because the maintainer has no Kerberos 5 server to test against. Use GSSAPI. +-------------------------------------------------------------------------------- +fetchmail-6.4.22 (not yet released): + +# SECURITY FIX: +* On IMAP connections, without --ssl and with nonempty --sslproto, meaning that + fetchmail is to enforce TLS, and when the server or an attacker sends + a PREAUTH greeting, fetchmail used to continue an unencrypted connection. + Now, log the error and abort the connection. + + Recommendation for servers that support SSL/TLS-wrapped or "implicit" mode on + a dedicated port (default 993): use --ssl. + + Reported by: Andrew C. Aitchison, based on the USENIX Security 21 paper "Why + TLS is better without STARTTLS - A Security Analysis of STARTTLS in the Email + Context" by Damian Poddebniak, Fabian Ising, Hanno Böck, and Sebastian + Schinzel. The paper did not mention fetchmail. + -------------------------------------------------------------------------------- fetchmail-6.4.21 (released 2021-08-09, 30042 LoC): -- cgit v1.2.3