# HG changeset patch
# User Antoine Pitrou <solipsis@pitrou.net>
# Date 1368892602 -7200
# Node ID c627638753e2d25a98950585b259104a025937a9
# Parent 9682241dc8fcb4b1aef083bd30860efa070c3d6d
Issue #17980: Fix possible abuse of ssl.match_hostname() for denial of service using certificates with many wildcards (CVE-2013-2099).
Index: backports.ssl_match_hostname-3.2a3/src/backports/ssl_match_hostname/__init__.py
===================================================================
--- backports.ssl_match_hostname-3.2a3.orig/src/backports/ssl_match_hostname/__init__.py
+++ backports.ssl_match_hostname-3.2a3/src/backports/ssl_match_hostname/__init__.py
@@ -7,9 +7,16 @@ __version__ = '3.2.2'
class CertificateError(ValueError):
pass
-def _dnsname_to_pat(dn):
+def _dnsname_to_pat(dn, max_wildcards=1):
pats = []
for frag in dn.split(r'.'):
+ if frag.count('*') > max_wildcards:
+ # Issue #17980: avoid denials of service by refusing more
+ # than one wildcard per fragment. A survery of established
+ # policy among SSL implementations showed it to be a
+ # reasonable choice.
+ raise CertificateError(
+ "too many wildcards in certificate DNS name: " + repr(dn))
if frag == '*':
# When '*' is a fragment by itself, it matches a non-empty dotless
# fragment.