OpenSSH 10.6, released 2026-10-06, introduces a faster cadence of point releases in response to a surge of security bug reports (many originating from or assisted by AI) and thanks contributors. It begins deprecating scp's -R remote-to-remote execution, and warns that support for platforms lacking file-descriptor passing and requiring root for PTY allocation (notably QNX 6 and SCO OpenServer 5) will be removed; on those platforms GatewayPorts and StreamLocalForwarding are forcibly disabled. Command-line destination usernames are now more strictly validated (disallowing $ and \), and compression effectiveness will be reduced because of a security-related change described below.
Security and robustness fixes include stricter sftp path validation to prevent recursive-copy escape, ensuring GSSAPI credentials are only stored on successful auth and resetting GSSAPI state between attempts, and bounds-checking compressed payloads. The LZ77 dictionary coder is disabled to mitigate a compression side-channel (chosen-plaintext) attack that can recover secrets via a shared compression dictionary. New features include a hybrid post-quantum ssh-mldsa44-ed25519 signature algorithm (old experimental keys must be regenerated), a server-side WarnWeakCrypto option, preservation of FIDO resident-key user-verification via credProtect, ssh-keygen hexdump export, ssh-add -P, sftp -p, AgentSocketPath/ssh-agent -A for agent socket handling, PubkeyOptions max-pk-ok to reduce auth failures from excessive PK_OK checks, TCPKeepAlive enhancements, and multiple platform and internationalization bugfixes.
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