From bc43c0d9468a8d50ba141c8a965f9f07ed0456ff Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Mon, 3 Aug 2020 19:20:05 +0200
Subject: libinterimap: Fix response injection vulnerability after STARTTLS.

For background see https://gitlab.com/muttmua/mutt/-/issues/248 .
---
 lib/Net/IMAP/InterIMAP.pm | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'lib')

diff --git a/lib/Net/IMAP/InterIMAP.pm b/lib/Net/IMAP/InterIMAP.pm
index 906d38b..f0dd2df 100644
--- a/lib/Net/IMAP/InterIMAP.pm
+++ b/lib/Net/IMAP/InterIMAP.pm
@@ -1654,6 +1654,11 @@ sub _start_ssl($$) {
     my $ctx = Net::SSLeay::CTX_new() or $self->panic("Failed to create SSL_CTX $!");
     my $ssl_options = Net::SSLeay::OP_SINGLE_DH_USE() | Net::SSLeay::OP_SINGLE_ECDH_USE();
 
+    if (defined $self->{_OUTBUF} and $self->{_OUTBUF} ne '') {
+        $self->warn("Truncating non-empty output buffer (unauthenticated response injection?)");
+        undef $self->{_OUTBUF};
+    }
+
     $self->{SSL_protocols} //= q{!SSLv2 !SSLv3 !TLSv1 !TLSv1.1};
     my ($proto_include, $proto_exclude) = (0, 0);
     foreach (split /\s+/, $self->{SSL_protocols}) {
-- 
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