https://cybertoolchain.io/tools/openssh New releases and features in OpenSSH, tracked by The Cyber Toolchain. en Tue, 06 Oct 2026 00:00:00 GMT https://www.openssh.com/txt/release-10.6 https://www.openssh.com/txt/release-10.6 Tue, 06 Oct 2026 00:00:00 GMT OpenSSH 10.6 adds post-quantum signatures, `WarnWeakCrypto` for sshd, `AgentSocketPath`, FIDO PIN-skip `-P`, and fractional `ChannelTimeout`.⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠ • Adds `WarnWeakCrypto` option to sshd_config(5), enabled by default, logging when a client uses a key-agreement scheme that is not post-quantum safe (previously client-only).⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠ • Adds `AgentSocketPath` option to sshd_config(5) to control the location of `$SSH_AUTH_SOCK` for agent forwarding, supporting `user:<path>` (e.g. `user:.ssh/agent`) and `shared:<path>` (e.g. `shared:/tmp`) directory styles; sockets in shared directories are created inside a subdirectory with a randomised name. • Adds `PubkeyOptions max-pk-ok:nnnn` to let a configurable number of PK_OK public-key probe tests proceed without counting against `MaxAuthTries`, defaulting to 6, allowing more keys in `ssh-agent` or on disk to be checked before disconnection. • Extends `TCPKeepAlive` in ssh(1) and sshd(8) to accept a new `all` value that additionally enables keepalives on forwarding sockets, not only the main connection socket (`yes`/`transport` retains the previous behaviour). • Enables hybrid post-quantum `ssh-mldsa44-ed25519` signature algorithm across all components; keys generated with the previous experimental (`@openssh.com`-suffixed) implementation must be regenerated. • Adds `-A` flag to ssh-agent(1) to specify agent socket directories, accepting the same `user:` and `shared:` styles as the new sshd `AgentSocketPath` option. • Adds `-P` flag to ssh-add(1) to skip PIN entry for FIDO and PKCS#11 tokens that do not require it. • Adds `hexdump` key export mode to ssh-keygen(1) (e.g. `ssh-keygen -em hexdump -f /key`) that dumps the SSH wire-formatted key blob in hex format. • Adds `-p` flag to sftp(1) `mkdir`/`lmkdir` subcommands to create parent directories as needed, analogous to `mkdir -p`, without erroring on pre-existing directories. • Allows `ChannelTimeout` in ssh(1) and sshd(8) to accept fractional-second timeout values. • Preserves user-verification (PIN or biometric) requirements for resident FIDO keys loaded from a token by checking the credential's `credProtect` policy in ssh-keygen(1) and ssh-add(1). • Includes local and remote SSH version strings in the `~I` connection information display in ssh(1). Breaking changes: • The `ssh-mldsa44-ed25519` algorithm no longer uses the `@openssh.com` vendor extension suffix; keys generated with the previous experimental implementation must be regenerated and/or removed. • Compression is less effective: the LZ77 dictionary coder is disabled in ssh(1) and sshd(8) to mitigate a cross-channel plaintext-recovery side-channel. • ssh(1) now rejects command-line usernames containing `$` or `\` characters; usernames specified via the `User` directive in config files are not affected. • On platforms that do not support file descriptor passing and require root for PTY allocation (e.g. QNX 6, SCO OpenServer 5, or builds with `--disable-fd-passing`), `GatewayPorts` and `StreamLocalForwarding` are forcibly disabled. • The `scp -R` flag now emits a deprecation warning to standard error; it will be ignored in a future release. • On OS X SDK >= 27, sshd(8) sandboxing is no longer supported as the required API has been removed. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Tue, 11 Aug 2026 15:43:18 GMT OpenSSH 10.5 adds `ssh -Z` key-preview mode, FIDO flag editing on passphrase reset, and smarter FIDO key ordering for pubkey auth. • Adds `ssh -Z user@host` mode that prints the public keys that will be tried for pubkey authentication, in the order they will be used. • Adds ability to set or clear the `touch-required` and `verify-required` flags on FIDO private keys when resetting a private key's passphrase. • Reorders FIDO key trials during pubkey authentication to prefer low-friction keys (no user presence required) before high-friction keys (PIN or biometric verification). • Makes `ssh-keyscan` banner reading non-blocking so a stuck server no longer stalls a multi-host keyscan. • Re-allows `PAMServiceName` inside a `Match` block in `sshd_config` (had been incorrectly disabled in 10.4). • Allows `ChannelTimeout` and `RekeyLimit` to be set inside `sshd_config` `Match` blocks. • Moves public key type check against allowed algorithms to before key parsing, reducing pre-authentication attack surface. Breaking changes: • Portable OpenSSH now requires ECC (Elliptic Curve Cryptography) support in libcrypto, including support for the NISTP521 curve; builds against a libcrypto without ECC will fail. The `--without-openssl` build configuration is not affected. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-10.5 https://www.openssh.com/txt/release-10.5 Tue, 11 Aug 2026 09:14:16 GMT OpenSSH 10.5 adds FIDO key flag editing, smart pubkey ordering, and a new `ssh -Z` auth-key inspection mode • New `ssh -Z user@host` mode prints the public keys that will be tried during authentication, in the exact order they will be attempted. • Adds ability in ssh-keygen(1) to set or clear the `touch-required` and `verify-required` flags on FIDO private keys when resetting a passphrase. • ssh(1) now tries FIDO keys that require no user presence first, and FIDO keys requiring PIN or biometric verification last, reducing unnecessary friction during pubkey authentication. • sshd(8) now uses setproctitle(3) to label the `sshd-session` process when acting as a post-authentication monitor, improving process visibility. Breaking changes: • Portable OpenSSH now requires ECC (Elliptic Curve Cryptography) support — including the NISTP521 curve — in libcrypto; builds against a libcrypto without ECC will fail. The `--without-openssl` build configuration is not affected. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.9 https://www.openssh.com/txt/release-9.9 Mon, 29 Jun 2026 22:50:58 GMT OpenSSH 9.9 defaults to ML-KEM post-quantum key exchange, drops DSA key support, and adds new signing tools. • Adds mlkem768x25519-sha256 hybrid post-quantum key exchange as the new default, replacing sntrup761x25519-sha512. • Removes DSA key support entirely — DSA host keys and user keys are no longer accepted (breaking change practitioners must act on). • Adds ssh-keygen -Y match-principals subcommand to test whether a principal is listed in an allowed-signers file. • Adds support for reading the list of authorized principals from a file via AuthorizedPrincipalsFile in combination with cert-based auth. • Enables ChannelTimeout and UnusedConnectionTimeout directives in sshd to terminate idle channels and unused connections automatically. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-10.3 https://www.openssh.com/txt/release-10.3 Thu, 02 Apr 2026 00:00:00 GMT OpenSSH 10.3 adds agent query extension, multi-file key directives, connection info commands, and ed25519/PKCS8 support. • Add `ssh-add -Q` to query the SSH agent's protocol extensions via the draft-ietf-sshm-ssh-agent "query" extension • Add `-J`/`ProxyJump` user and host name validation on the command line for ssh(1) • Support multiple files in the `sshd_config RevokedKeys` directive • Add `~I` escape option to show current SSH connection information • Add `ssh -O conninfo user@host` multiplexing subcommand to display connection info • Add `ssh -O channels user@host` multiplexing subcommand to list open channels • Add 'invaliduser' penalty option to `PerSourcePenalties` in `sshd_config` • Add `GSSAPIDelegateCredentials` server option in `sshd_config` • Support VA DSCP codepoint in the `IPQoS` directive for ssh(1) and sshd(8) • Convert `PerSourcePenalties` to floating point time for sub-second granularity Breaking changes: • Removed bug compatibility for SSH implementations that do not support rekeying; connections with such peers will fail during transport rekeying. • Changed handling of certificates with an empty principals section via `authorized_keys principals=""` option: previously matched any principal (wildcard), now matches never, preventing accidental wildcard authentication. • Wildcard characters in certificate principals are now consistently implemented for host certificates and unsupported for user certificates. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-10.1 https://www.openssh.com/txt/release-10.1 Mon, 06 Oct 2025 00:00:00 GMT OpenSSH 10.1 adds `RefuseConnection`, `-N` to ssh-add, PKCS#11 ed25519, and improved DSCP handling • Adds `RefuseConnection` ssh_config option for early connection termination in config files. • Adds `ssh-add -N` option to disable automatic certificate expiry grace periods. • Supports ed25519 keys on PKCS#11 tokens via ssh(1) and ssh-agent(1). • Adds `WarnWeakCrypto` ssh_config option to control warnings for non-post-quantum key exchange algorithms. • Moves default ssh-agent socket path from `/tmp` to `$HOME/.ssh/agent` with new flags `-U`, `-u`, `-uu`, and `-T`. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-10.0 https://www.openssh.com/txt/release-10.0 Wed, 09 Apr 2025 00:00:00 GMT OpenSSH 10.0 adds post-quantum KEX, new ssh_config Match directives, scoped key deletion and glob-based auth file matching. • ssh(1) now defaults to the hybrid post-quantum `mlkem768x25519-sha256` key agreement algorithm for connections. • Adds support for `Match version`, `Match sessiontype`, and `Match command` in `ssh_config` for granular conditional configuration. • Adds `-Owebsafe-allow=...` option to ssh-agent(1) to override the default FIDO application ID allow-list. • sshd(8) now disables finite field (modp) Diffie-Hellman key exchange methods from `KEXAlgorithms` by default, keeping only Elliptic Curve and Post-Quantum options. • Adds glob pattern support to `AuthorizedKeysFile` and `AuthorizedPrincipalsFile` in `sshd_config` via glob(3). • ssh-agent(1) now deletes all loaded keys when signaled with `SIGUSR1`, allowing key deletion without `$SSH_AUTH_SOCK`. • Adds `SetEnv` directive support for `%`-tokens and environment variable expansion in `ssh_config`. Breaking changes: • Removal of the DSA signature algorithm support (completing deprecation started in 2015). • sshd(8) removes finite field (modp) Diffie-Hellman key exchange from default `KEXAlgorithms`, which may cause connections to older servers or clients relying on modp to fail. • The version string is now "SSH-2.0-OpenSSH_10.0"; scripts matching "OpenSSH_1*" may misidentify the version. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.9 https://www.openssh.com/txt/release-9.9 Thu, 19 Sep 2024 00:00:00 GMT OpenSSH 9.9 adds ML-KEM post-quantum KEX, RefuseConnection, invalid-user Match, env expansion in Include, and core dump protection • ssh(1), sshd(8): add `mlkem768x25519-sha256` hybrid post-quantum key exchange algorithm (ML-KEM + X25519), available by default • `ssh_config` `Include` directive now expands environment variables • `sshd_config`: add `RefuseConnection` option to terminate connections at the first authentication request • `sshd_config` `PerSourcePenalties`: new `refuseconnection` penalty class for dropped connections • `sshd_config` `Match invalid-user` predicate to match when the target username is not valid on the server • Private keys are kept out of core dump files for most of their lifespan across `ssh`, `sshd`, and `ssh-agent` (OpenBSD, Linux, FreeBSD) Breaking changes: • ssh(1): removal of pre-authentication compression support • Match configuration directive arguments now follow stricter shell-like quote rules; workarounds for previous simplistic quote handling may need adjustment, especially in `Match exec` conditions Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.8 https://www.openssh.com/txt/release-9.8 Mon, 01 Jul 2024 00:00:00 GMT OpenSSH 9.8 adds PerSourcePenities for automated client blocking and splits sshd into listener/session binaries. • Adds `PerSourcePenalties` and `PerSourcePenaltyExemptList` to sshd_config(5) to automatically block IP addresses that fail authentication or crash the server. • Splits the sshd(8) binary into a lightweight listener and a per-session `sshd-session` binary, removing support for disabling privilege separation or re-execution. • Adds `-q` flag to ssh-keyscan(1) to suppress hostname and banner comment lines that previously went to stderr. • Introduces `PAMServiceName` directive in sshd_config(5) (portable OpenSSH only) to explicitly set the PAM service name instead of relying on `argv[0]`. Breaking changes: • Support for disabling privilege separation in sshd(8) is removed; previously required code changes are no longer supported. • Support for disabling re-execution of sshd(8) is removed. • sshd(8) (portable OpenSSH only) no longer uses argv[0] as the PAM service name; use `PAMServiceName` in sshd_config(5) to configure it. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.7 https://www.openssh.com/txt/release-9.7 Mon, 11 Mar 2024 00:00:00 GMT OpenSSH 9.7 introduces `ChannelTimeout` global mode for idle channel management. • Adds a new "global" value to the `ChannelTimeout` directive that closes all open channels if any remain idle for the specified duration • Makes DSA key support compile-time optional via `WITHOUT_DSA` build flag, defaulting to enabled in this release Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.6 https://www.openssh.com/txt/release-9.6 Mon, 18 Dec 2023 00:00:00 GMT OpenSSH 9.6 adds strict KEX for Terrapin defense, %j ProxyJump token, ChannelTimeout, PEM PKCS8 keys, and agent-cert PKCS11 loading • Adds `%j` token in ssh_config(5) that expands to the configured ProxyJump hostname. • Adds `ChannelTimeout` support to ssh(1) client, allowing termination of quiescent channels. • Adds support for reading ED25519 private keys in PEM PKCS8 format via ssh(1), sshd(8), ssh-add(1), and ssh-keygen(1). • Introduces a protocol extension allowing renegotiation of acceptable signature algorithms for public key authentication after the server learns the username, enabling `PubkeyAcceptedAlgorithms` in `Match user` blocks. • Adds an agent protocol extension to ssh-add(1) and ssh-agent(1) allowing specifying certificates when loading PKCS#11 keys. Breaking changes: • The RFC4254 connection/channels window limit now causes ssh(1) or sshd(8) to terminate the connection if a peer exceeds the limit by more than a small grace factor, whereas previously extra data was discarded. • Invalid user or hostnames containing shell metacharacters supplied via the command-line are now banned, whereas they were previously passed through (potentially causing injection). Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.5 https://www.openssh.com/txt/release-9.5 Wed, 04 Oct 2023 00:00:00 GMT OpenSSH 9.5 adds keystroke timing obfuscation and transport-level ping support. • Adds `ObscureKeystrokeTiming` to `ssh_config` to hide inter-keystroke timings for enhanced privacy against traffic analysis • Introduces transport-level ping capability via `SSH2_MSG_PING/PONG` messages in both client and server Breaking changes: • ssh-keygen(1) now generates Ed25519 keys by default, overriding previous key type defaults • The Subsystem directive in sshd(8) now accurately preserves quoting of subsystem commands and arguments Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.4 https://www.openssh.com/txt/release-9.4 Thu, 10 Aug 2023 00:00:00 GMT OpenSSH 9.4 adds Unix socket forwarding, Tag/Localnetwork config predicates, KRL wire format support, and new %-expansion sequences. • `ssh -W` now forwards Unix Domain sockets via `ProxyJump` • `Match tag` predicate added to ssh_config(5) alongside the `Tag` directive • `match localnetwork` predicate added to `Match` blocks in `ssh_config` • Wire format infrastructure for KRL extensions defined in ssh-keygen, ssh-agent, and sshd • %D (routing domain) and %C (source/destination addresses and port numbers) %-expansion sequences added to AuthorizedPrincipalsCommand and AuthorizedKeysCommand in sshd_config Breaking changes: • Removes support for older versions of libcrypto; requires LibreSSL >= 3.1.0 or OpenSSL >= 1.1.1. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.3p2 https://www.openssh.com/txt/release-9.3p2 Wed, 19 Jul 2023 00:00:00 GMT OpenSSH 9.3p2 adds `ssh-agent -P` and `-Oallow-remote-pkcs11` to mitigate PKCS#11 remote code execution via CVE-2023-38408. • Adds the `-P` flag to ssh-agent(1) to configure an empty or specific allowlist of PKCS#11/FIDO provider libraries, restricting which modules can be loaded during agent forwarding. Breaking changes: • By default, ssh-agent(8) now refuses requests to load PKCS#11 modules issued by remote clients; use `-Oallow-remote-pkcs11` to restore the previous behavior. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Wed, 19 Jul 2023 00:00:00 GMT OpenSSH 9.3p2 adds `ssh-agent -Oallow-remote-pkcs11` and restricts remote PKCS#11 loading by default. • Adds `-Oallow-remote-pkcs11` flag to `ssh-agent` to restore previous behavior of allowing remote clients to load PKCS#11 modules • Changes ssh-agent(1) default to refuse requests to load PKCS#11 modules issued by remote clients Breaking changes: • The ssh-agent(8) agent now refuses requests to load PKCS#11 modules issued by remote clients by default; use the `-Oallow-remote-pkcs11` flag to restore the previous behavior. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.com/txt/release-9.3 https://www.openssh.com/txt/release-9.3 Wed, 15 Mar 2023 00:00:00 GMT OpenSSH 9.3 adds -G for effective config preview and -Ohashalg for SSHFP output control. • Adds `sshd -G` flag to parse and print the effective configuration without loading private keys, enabling verification by unprivileged users before key generation. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Thu, 02 Feb 2023 00:00:00 GMT OpenSSH 9.2 adds ChannelTimeout and UnusedConnectionTimeout directives, ~C escape command-line toggle, and -X for scp/sftp. • Adds `ChannelTimeout` directive to sshd_config(5) for channel inactivity timeouts • Adds `UnusedConnectionTimeout` option to `sshd_config` to terminate idle client connections • Adds new `EnableEscapeCommandline` ssh_config option defaulting to 'no' to control the ~C escape sequence Breaking changes: • `EnableEscapeCommandline` defaults to 'no', disabling the previously enabled default `~C` command-line escape sequence for ssh clients. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Tue, 04 Oct 2022 00:00:00 GMT OpenSSH 9.1 adds RequiredRSASize directive, SFTP users-groups-by-id extension, and UTC date parsing • Adds `RequiredRSASize` directive to `ssh_config` and `sshd_config` to set a minimum RSA key length. • Introduces `users-groups-by-id@openssh.com` SFTP extension for resolving UIDs/GIDs to names in directory listings. • Allows `ssh-keygen` date arguments to accept UTC suffixed with 'Z' and hex epoch values. • Enables `-U` flag with `-Y sign` in `ssh-keygen` to require keys be hosted in an agent. Breaking changes: • `SetEnv` directives in `ssh_config` and `sshd_config` are now first-match-wins to match other directives. • `ssh-keygen -A` will no longer generate DSA keys. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Fri, 08 Apr 2022 00:00:00 GMT OpenSSH 9.0 adds `cp` subcommand to sftp and defaults to hybrid NTRU+X25519 key exchange. • scp(1) defaults to the SFTP protocol instead of the legacy scp/rcp protocol, removing the need for double-quoting shell meta-characters in remote paths; use `-O` to revert. • Adds `sntrup761x25519-sha512@openssh.com` (hybrid Streamlined NTRU Prime + x25519) as the default key exchange method for ssh(1) and sshd(8) to mitigate 'capture now, decrypt later' attacks. • Adds support for the `copy-data` extension in sftp-server(8) to enable server-side file copying. • Adds a new `cp` command to the sftp(1) client to perform server-side file copies using the new extension. Breaking changes: • scp(1) no longer uses the legacy scp/rcp protocol by default; remote wildcard expansion (e.g., `host:*`) now happens on the client side via SFTP, so double-quoting shell meta-characters in filenames will cause transfers to fail instead of being passed through. • scp(1) clients connecting to servers that do not support the `expand-path@openssh.com` extension cannot expand remote paths relative to other users' home directories (e.g., `host:~user/file`). Use `-O` to restore legacy behavior. Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh https://www.openssh.org/releasenotes.html https://www.openssh.org/releasenotes.html Wed, 23 Feb 2022 00:00:00 GMT OpenSSH 8.9 adds sntrup761x25519 post-quantum KEX, agent key restrictions, and ssh-keygen match-principals • `sntrup761x25519-sha512@openssh.com` hybrid ECDH/x25519 + Streamlined NTRU Prime post-quantum KEX added to the default `KEXAlgorithms` list • System for restricting forwarding and use of keys added to ssh-agent(1) (agent-restricted keys) • `ssh-keygen -Y match-principals` operation added to perform matching of principals names against an allowed signers file • `PubkeyAuthentication` configuration directive extended to accept `unbound` and `host-bound` options Breaking changes: • Built-in support for MD5-hashed passwords is removed from sshd(8) on portable OpenSSH • FIDO security key middleware interface modified, incrementing `SSH_SK_VERSION_MAJOR` Full history on Cyber Toolchain: https://cybertoolchain.io/tools/openssh