# HG changeset patch
# User R David Murray <rdmurray@bitdance.com>
# Date 1388775562 18000
# Node ID dd906f4ab9237020a7a275c2d361fa288e553481
# Parent 69b5f692455306c98aa27ecea17e6290787ebd3f
closes 16039: CVE-2013-1752: limit line length in imaplib readline calls.
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -35,6 +35,15 @@ IMAP4_PORT = 143
IMAP4_SSL_PORT = 993
AllowedVersions = ('IMAP4REV1', 'IMAP4') # Most recent first
+# Maximal line length when calling readline(). This is to prevent
+# reading arbitrary length lines. RFC 3501 and 2060 (IMAP 4rev1)
+# don't specify a line length. RFC 2683 however suggests limiting client
+# command lines to 1000 octets and server command lines to 8000 octets.
+# We have selected 10000 for some extra margin and since that is supposedly
+# also what UW and Panda IMAP does.
+_MAXLINE = 10000
+
+
# Commands
Commands = {
@@ -237,7 +246,10 @@ class IMAP4:
def readline(self):
"""Read line from remote."""
- return self.file.readline()
+ line = self.file.readline(_MAXLINE + 1)
+ if len(line) > _MAXLINE:
+ raise self.error("got more than %d bytes" % _MAXLINE)
+ return line
def send(self, data):
diff --git a/Lib/test/test_imaplib.py b/Lib/test/test_imaplib.py
--- a/Lib/test/test_imaplib.py
+++ b/Lib/test/test_imaplib.py
@@ -165,6 +165,16 @@ class BaseThreadedNetworkedTests(unittes
self.imap_class, *server.server_address)
+ def test_linetoolong(self):
+ class TooLongHandler(SimpleIMAPHandler):
+ def handle(self):
+ # Send a very long response line
+ self.wfile.write('* OK ' + imaplib._MAXLINE*'x' + '\r\n')
+
+ with self.reaped_server(TooLongHandler) as server:
+ self.assertRaises(imaplib.IMAP4.error,
+ self.imap_class, *server.server_address)
+
class ThreadedNetworkedTests(BaseThreadedNetworkedTests):
server_class = SocketServer.TCPServer