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Date: Thu, 05 Mar 2015 11:36:45 -0700
From: Kurt Seifried <>
Subject: Re: Another Python app (rhn-setup: rhnreg_ks) not
 checking hostnames in certs properly CVE-2015-1777

On 05/03/15 10:06 AM, John Haxby wrote:
> PEP 476 cites 11 CVEs that resulted from python not properly validating
> certificates.   This would be number 12.
> Shouldn't python versions prior to 2.7.9 and 3.4.3 have a CVE each for
> the lack of verification? If internal corporate software stops working
> because of invalid certificates, wasn't it broken anyway?

So if something is advertised as having a security feature and does not
or it is broken then it gets a CVE. In this case Python, and basically
every other SSL/TLS implementation on the planet, by default, did not
check hostnames in certs, but they did provide that capability should
you choose to use it. So no CVE since it wasn't "meant to be secure" as
I understand it.

Now for my personal opinion: Doing SSL/TLS with server certs and not
checking the hostname in a server cert is completely insane and utterly
defeats the purpose. However there are cases where a certificate may not
have a hostname field, or need a valid hostname field, e.g. a client
certificate where you mostly care about the fact that the client has it
at all. So I can see why they made hostname checks optional, but again,
I think it was a very bad decision long term as evidenced by:

> jch

Kurt Seifried -- Red Hat -- Product Security -- Cloud
PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993

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