closes 16039: CVE-2013-1752: limit line length in imaplib readline calls.
diff --git a/Lib/imaplib.py b/Lib/imaplib.py
index c576927..4586fb3 100644
--- a/Lib/imaplib.py
+++ b/Lib/imaplib.py
@@ -35,6 +35,15 @@
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 @@
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):