ssl: NULL in subjectAltNames

SSL module fails to handle NULL bytes inside subjectAltNames general names.

It’s related to Ruby’s CVE-2013-4073.

Issue #18709 reported by Christian Heimes at 2013-08-12.

Dates:

  • Disclosure date: 2013-06-27 (Ruby issue)
  • Reported by: Ryan Sleevi of the Google Chrome Security Team

Fixed In

Python issue

SSL module fails to handle NULL bytes inside subjectAltNames general names (CVE-2013-4238).

  • Python issue: bpo-18709
  • Creation date: 2013-08-12
  • Reporter: Christian Heimes

CVE-2013-4238

The ssl.match_hostname function in the SSL module in Python 2.6 through 3.4 does not properly handle a ‘0’ character in a domain name in the Subject Alternative Name field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.

Timeline

Timeline using the disclosure date 2013-06-27 as reference:

  • 2013-06-27: Disclosure date (Ruby issue)
  • 2013-08-12 (+46 days): Python issue bpo-18709 reported by Christian Heimes
  • 2013-08-16 (+50 days): commit 824f7f3 (branch 3.3)
  • 2013-08-18 (+52 days): CVE-2013-4238 published
  • 2013-08-23 (+57 days): commit 82f8828 (branch 2.7)
  • 2013-10-29 (+124 days): Python 2.6.9 released
  • 2013-11-10 (+136 days): Python 2.7.6 released
  • 2013-11-17 (+143 days): Python 3.3.3 released
  • 2014-03-16: Python 3.4.0 released
  • 2014-09-30 (+460 days): commit ec3c103 (branch 3.2)
  • 2014-10-12 (+472 days): Python 3.2.6 released