Announce: OpenSSH 9.1 released

Damien Miller djm at
Tue Oct 4 21:42:06 AEDT 2022

OpenSSH 9.1 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 9.0

This release is focused on bug fixing.


This release contains fixes for three minor memory safety problems.
None are believed to be exploitable, but we report most memory safety
problems as potential security vulnerabilities out of caution.

 * ssh-keyscan(1): fix a one-byte overflow in SSH- banner processing.
   Reported by Qualys

 * ssh-keygen(1): double free() in error path of file hashing step in
   signing/verify code; GHPR333

 * ssh-keysign(8): double-free in error path introduced in openssh-8.9

Potentially-incompatible changes

 * The portable OpenSSH project now signs commits and release tags
   using git's recent SSH signature support. The list of developer
   signing keys is included in the repository as .git_allowed_signers
   and is cross-signed using the PGP key that is still used to sign
   release artifacts:

 * ssh(1), sshd(8): SetEnv directives in ssh_config and sshd_config
   are now first-match-wins to match other directives. Previously
   if an environment variable was multiply specified the last set
   value would have been used. bz3438

 * ssh-keygen(8): ssh-keygen -A (generate all default host key types)
   will no longer generate DSA keys, as these are insecure and have
   not been used by default for some years.

New features

 * ssh(1), sshd(8): add a RequiredRSASize directive to set a minimum
   RSA key length. Keys below this length will be ignored for user
   authentication and for host authentication in sshd(8). 

   ssh(1) will terminate a connection if the server offers an RSA key
   that falls below this limit, as the SSH protocol does not include
   the ability to retry a failed key exchange.

 * sftp-server(8): add a "users-groups-by-id at" extension
   request that allows the client to obtain user/group names that
   correspond to a set of uids/gids.

 * sftp(1): use "users-groups-by-id at" sftp-server
   extension (when available) to fill in user/group names for
   directory listings.

 * sftp-server(8): support the "home-directory" extension request
   defined in draft-ietf-secsh-filexfer-extensions-00. This overlaps
   a bit with the existing "expand-path at", but some other
   clients support it.

 * ssh-keygen(1), sshd(8): allow certificate validity intervals,
   sshsig verification times and authorized_keys expiry-time options
   to accept dates in the UTC time zone in addition to the default
   of interpreting them in the system time zone. YYYYMMDD and
   YYMMDDHHMM[SS] dates/times will be interpreted as UTC if suffixed
   with a 'Z' character.

   Also allow certificate validity intervals to be specified in raw
   seconds-since-epoch as hex value, e.g. -V 0x1234:0x4567890. This
   is intended for use by regress tests and other tools that call
   ssh-keygen as part of a CA workflow. bz3468

 * sftp(1): allow arguments to the sftp -D option, e.g. sftp -D
   "/usr/libexec/sftp-server -el debug3"

 * ssh-keygen(1): allow the existing -U (use agent) flag to work
   with "-Y sign" operations, where it will be interpreted to require
   that the private keys is hosted in an agent; bz3429


 * ssh-keygen(1): implement the "verify-required" certificate option.
   This was already documented when support for user-verified FIDO
   keys was added, but the ssh-keygen(1) code was missing.

 * ssh-agent(1): hook up the restrict_websafe command-line flag;
   previously the flag was accepted but never actually used.

 * sftp(1): improve filename tab completions: never try to complete
   names to non-existent commands, and better match the completion
   type (local or remote filename) against the argument position
   being completed.

 * ssh-keygen(1), ssh(1), ssh-agent(1): several fixes to FIDO key
   handling, especially relating to keys that request
   user-verification. These should reduce the number of unnecessary
   PIN prompts for keys that support intrinsic user verification.
   GHPR302, GHPR329

 * ssh-keygen(1): when enrolling a FIDO resident key, check if a
   credential with matching application and user ID strings already
   exists and, if so, prompt the user for confirmation before
   overwriting the credential. GHPR329

 * sshd(8): improve logging of errors when opening authorized_keys
   files. bz2042

 * ssh(1): avoid multiplexing operations that could cause SIGPIPE from
   causing the client to exit early. bz3454

 * ssh_config(5), sshd_config(5): clarify that the RekeyLimit
   directive applies to both transmitted and received data. GHPR328

 * ssh-keygen(1): avoid double fclose() in error path.

 * sshd(8): log an error if pipe() fails while accepting a
   connection. bz3447

 * ssh(1), ssh-keygen(1): fix possible NULL deref when built without
   FIDO support. bz3443

 * ssh-keyscan(1): add missing *-sk types to ssh-keyscan manpage.

 * sshd(8): ensure that authentication passwords are cleared from
   memory in error paths. GHPR286

 * ssh(1), ssh-agent(1): avoid possibility of notifier code executing
   kill(-1). GHPR286

 * ssh_config(5): note that the ProxyJump directive also accepts the
   same tokens as ProxyCommand. GHPR305.

 * scp(1): do not not ftruncate(3) files early when in sftp mode. The
   previous behaviour of unconditionally truncating the destination
   file would cause "scp ~/foo localhost:foo" and the reverse
   "scp localhost:foo ~/foo" to delete all the contents of their
   destination. bz3431

 * ssh-keygen(1): improve error message when 'ssh-keygen -Y sign' is
   unable to load a private key; bz3429

 * sftp(1), scp(1): when performing operations that glob(3) a remote
   path, ensure that the implicit working directory used to construct
   that path escapes glob(3) characters. This prevents glob characters
   from being processed in places they shouldn't, e.g. "cd /tmp/a*/",
   "get *.txt" should have the get operation treat the path "/tmp/a*"
   literally and not attempt to expand it.

 * ssh(1), sshd(8): be stricter in which characters will be accepted
   in specifying a mask length; allow only 0-9. GHPR278

 * ssh-keygen(1): avoid printing hash algorithm twice when dumping a

 * ssh(1), sshd(8): continue running local I/O for open channels
   during SSH transport rekeying. This should make ~-escapes work in
   the client (e.g. to exit) if the connection happened to have
   stalled during a rekey event.

 * ssh(1), sshd(8): avoid potential poll() spin during rekeying

 * Further hardening for sshbuf internals: disallow "reparenting" a
   hierarchical sshbuf and zero the entire buffer if reallocation
   fails. GHPR287


 * ssh(1), ssh-keygen(1), sshd(8): automatically enable the built-in
   FIDO security key support if libfido2 is found and usable, unless
   --without-security-key-builtin was requested.

 * ssh(1), ssh-keygen(1), sshd(8): many fixes to make the WinHello
   FIDO device usable on Cygwin. The windows://hello FIDO device will
   be automatically used by default on this platform unless requested
   otherwise, or when probing resident FIDO credentials (an operation
   not currently supported by WinHello).

 * Portable OpenSSH: remove workarounds for obsolete and unsupported
   versions of OpenSSL libcrypto. In particular, this release removes
   fallback support for OpenSSL that lacks AES-CTR or AES-GCM.

   Those AES cipher modes were added to OpenSSL prior to the minimum
   version currently supported by OpenSSH, so this is not expected to
   impact any currently supported configurations.

 * sshd(8): fix SANDBOX_SECCOMP_FILTER_DEBUG on current Linux/glibc

 * All: resync and clean up internal CSPRNG code.

 * scp(1), sftp(1), sftp-server(8): avoid linking these programs with
   unnecessary libraries. They are no longer linked against libz and
   libcrypto. This may be of benefit to space constrained systems
   using any of those components in isolation.

 * sshd(8): add AUDIT_ARCH_PPC to supported seccomp sandbox

 * configure: remove special casing of crypt(). configure will no
   longer search for crypt() in libcrypto, as it was removed from
   there years ago. configure will now only search libc and libcrypt.

 * configure: refuse to use OpenSSL 3.0.4 due to potential RCE in its
   RSA implementation (CVE-2022-2274) on x86_64.

 * All: request 1.1x API compatibility for OpenSSL >=3.x; GHPR#322

 * ssh(1), ssh-keygen(1), sshd(8): fix a number of missing includes
   required by the XMSS code on some platforms.

 * sshd(8): cache timezone data in capsicum sandbox.


- SHA1 (openssh-9.1.tar.gz) = 3ae2d6a3a695d92778c4c4567dcd6ad481092f6c
- SHA256 (openssh-9.1.tar.gz) = QKfVArlcItV+e8V1Th85TL5//5d/AvOUhYOeHMDEGuE=

- SHA1 (openssh-9.1p1.tar.gz) = 15545440268967511d3194ebf20bcd0c7ff3fcc9
- SHA256 (openssh-9.1p1.tar.gz) = GfhQCcfj4jeH8CNvuxV4OSq01L+fjsX+a8HNfov90og=

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 openssh at

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