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Date: Thu, 20 Jul 2023 09:24:21 -0400
From: Demi Marie Obenour <>
Subject: Re: Announce: OpenSSH 9.3p2 released

On Wed, Jul 19, 2023 at 08:40:40AM -0600, Damien Miller wrote:
> OpenSSH 9.3p2 has just been released. It will be available from the
> mirrors listed at shortly.
> OpenSSH is a 100% complete SSH protocol 2.0 implementation and
> includes sftp client and server support.
> Once again, we would like to thank the OpenSSH community for their
> continued support of the project, especially those who contributed
> code or patches, reported bugs, tested snapshots or donated to the
> project. More information on donations may be found at:
> Changes since OpenSSH 9.3
> =========================
> This release fixes a security bug.
> Security
> ========
> Fix CVE-2023-38408 - a condition where specific libaries loaded via
> ssh-agent(1)'s PKCS#11 support could be abused to achieve remote
> code execution via a forwarded agent socket if the following
> conditions are met:
> * Exploitation requires the presence of specific libraries on
>   the victim system.
> * Remote exploitation requires that the agent was forwarded
>   to an attacker-controlled system.
> Exploitation can also be prevented by starting ssh-agent(1) with an
> empty PKCS#11/FIDO allowlist (ssh-agent -P '') or by configuring
> an allowlist that contains only specific provider libraries.
> This vulnerability was discovered and demonstrated to be exploitable
> by the Qualys Security Advisory team. 
> In addition to removing the main precondition for exploitation,
> this release removes the ability for remote ssh-agent(1) clients
> to load PKCS#11 modules by default (see below).
> Potentially-incompatible changes
> --------------------------------
>  * ssh-agent(8): the agent will now refuse requests to load PKCS#11
>    modules issued by remote clients by default. A flag has been added
>    to restore the previous behaviour "-Oallow-remote-pkcs11".
>    Note that ssh-agent(8) depends on the SSH client to identify
>    requests that are remote. The OpenSSH >=8.9 ssh(1) client does
>    this, but forwarding access to an agent socket using other tools
>    may circumvent this restriction.
> Checksums:
> ==========
> - SHA1 (openssh-9.3p2.tar.gz) = 219cf700c317f400bb20b001c0406056f7188ea4
> - SHA256 (openssh-9.3p2.tar.gz) = IA6+FH9ss/EB/QzfngJEKvfdyimN/9n0VoeOfMrGdug=
> Please note that the SHA256 signatures are base64 encoded and not
> hexadecimal (which is the default for most checksum tools). The PGP
> key used to sign the releases is available from the mirror sites:
> Reporting Bugs:
> ===============
> - Please read
>   Security bugs should be reported directly to

Should there be a system-wide configuration file containing a list of
known-good PKCS#11 libraries?  ssh-agent having to guess if something is
a PKCS#11 library is less than awesome.
Demi Marie Obenour (she/her/hers)
Invisible Things Lab

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