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Date: Fri, 2 Oct 2015 16:16:14 +0200
From: Gilles Chehade <>
To: "Jason A. Donenfeld" <>
Cc: oss-security <>,
	misc <>
Subject: Re: CVE requests: Critical vulnerabilities in OpenSMTPD

On Fri, Oct 02, 2015 at 03:22:01PM +0200, Jason A. Donenfeld wrote:
> Hello,


> See this excerpt from the release notes below. Quite a few bugs. Looks
> like at least one of them might invalidate the claim,
> "Only two remote holes in the default install, in a heck of a long
> time!".

Not really, no.

By default, the MTA operates in local-mode only accepting connections on
the loopback interface and through the unix socket. This is also true on
OpenSMTPD -portable.

Not to mention that remote vulnerabilities only affect a process that is
unprivileged and that the local vulnerabilities, as far as I know, don't
allow for privileges escalation, only leaking of a hash (yes, it is bad,
but you don't suddenly compromise the machine either).

> CCing the OpenSMTPD mailing list (low-volume; don't worry Solar!) in
> case they want to chime in too.

I'll chime in.

As we made clear in the commits and release note these issues were found
by Qualys Security during an audit, for which they're going to publish a
detailed advisory (very good read) with CVE associated to each issue.

> ---------- Forwarded message ----------
> From: Gilles Chehade <>
> Date: Fri, Oct 2, 2015 at 4:01 AM
> Subject: Announce: OpenSMTPD 5.7.2 released
> To:
> [...snip...]
> Issues fixed in this release (5.7.2, since 5.7.1):
> ===========================================
> - an oversight in the portable version of fgetln() that allows attackers
>   to read and write out-of-bounds memory;
> - multiple denial-of-service vulnerabilities that allow local users to
>   kill or hang OpenSMTPD;
> - a stack-based buffer overflow that allows local users to crash
>   OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;
> - a hardlink attack (or race-conditioned symlink attack) that allows
>   local users to unset the chflags() of arbitrary files;
> - a hardlink attack that allows local users to read the first line of
>   arbitrary files (for example, root's hash from /etc/master.passwd);
> - a denial-of-service vulnerability that allows remote attackers to fill
>   OpenSMTPD's queue or mailbox hard-disk partition;
> - an out-of-bounds memory read that allows remote attackers to crash
>   OpenSMTPD, or leak information and defeat the ASLR protection;
> - a use-after-free vulnerability that allows remote attackers to crash
>   OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;
> -- 
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Gilles Chehade                                          @poolpOrg

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