From 1002a0121a8f5a9aee25357769807f2c519fa50b Mon Sep 17 00:00:00 2001

From: Damian Poddebniak <duesee@users.noreply.github.com>

Date: Fri, 24 Jul 2020 19:39:53 +0200

Subject: [PATCH 1/2] Detect extra data after STARTTLS response and exit (#387)

---

 src/low-level/imap/mailimap.c | 7 +++++++

 1 file changed, 7 insertions(+)

diff --git a/src/low-level/imap/mailimap.c b/src/low-level/imap/mailimap.c

index bb17119..4ffcf55 100644

--- a/src/low-level/imap/mailimap.c

+++ b/src/low-level/imap/mailimap.c

@@ -2428,6 +2428,13 @@ int mailimap_starttls(mailimap * session)

   mailimap_response_free(response);

+  // Detect if the server send extra data after the STARTTLS response.

+  // This *may* be a "response injection attack".

+  if (session->imap_stream->read_buffer_len != 0) {

+      // Since it is also an IMAP protocol violation, exit.

+      return MAILIMAP_ERROR_STARTTLS;

+  }

+

   switch (error_code) {

   case MAILIMAP_RESP_COND_STATE_OK:

     return MAILIMAP_NO_ERROR;

-- 

2.26.2