[Python-Dev] OpenSSL Security Advisory [9 Jul 2015]

Christian Heimes christian at python.org
Thu Jul 9 15:29:25 CEST 2015


this just came in. According to Zachary all Windows builds use 1.0.2c.
The version is vulnerable to a critical bug in the CA validation code of
OpenSSL. The bug can be abused to turn any valid server certificate into
a CA cert.

We should consider a security release of Python ASAP.

Alternative chains certificate forgery (CVE-2015-1793)

Severity: High

During certificate verification, OpenSSL (starting from version 1.0.1n
and 1.0.2b) will attempt to find an alternative certificate chain if the
first attempt to build such a chain fails. An error in the
implementation of this logic can mean that an attacker could cause
certain checks on untrusted certificates to be bypassed, such as the CA
flag, enabling them to use a valid leaf certificate to act as a CA and
"issue" an invalid certificate.

This issue will impact any application that verifies certificates
including SSL/TLS/DTLS clients and SSL/TLS/DTLS servers using client

This issue affects OpenSSL versions 1.0.2c, 1.0.2b, 1.0.1n and 1.0.1o.

OpenSSL 1.0.2b/1.0.2c users should upgrade to 1.0.2d
OpenSSL 1.0.1n/1.0.1o users should upgrade to 1.0.1p

This issue was reported to OpenSSL on 24th June 2015 by Adam
Langley/David Benjamin (Google/BoringSSL). The fix was developed by the
BoringSSL project.


As per our previous announcements and our Release Strategy
(https://www.openssl.org/about/releasestrat.html), support for OpenSSL
versions 1.0.0 and 0.9.8 will cease on 31st December 2015. No security
updates for these releases will be provided after that date. Users of
these releases are advised to upgrade.


URL for this Security Advisory:

Note: the online version of the advisory may be updated with additional
details over time.

For details of OpenSSL severity classifications please see:

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