OpenSSH 10.6 Enables Hybrid Post-Quantum Signatures; Experimental Keys Must Be Replaced
Summary
OpenSSH 10.6 introduces more frequent releases, disables LZ77 compression to reduce cross-channel attacks, fixes credential, path, and certificate handling, and enables a hybrid post-quantum signature algorithm. Earlier experimental keys must be regenerated or removed.
Key points
- The OpenSSH team plans more frequent releases after receiving numerous security reports, including bugs found with AI assistance.
- SSH and sshd disable the LZ77 dictionary coder to reduce cross-channel attacks that can expose secrets through shared compression state.
- The ssh client rejects command-line usernames containing dollar signs or backslashes because they could enable shell-context injection; usernames set in config files are exempt.
- sshd now stores GSSAPI credentials only after successful authentication, while sftp validates server-returned paths more strictly.
- ssh-keygen fixes certificate expiry-time errors related to Daylight Saving Time.
- OpenSSH 10.6 enables the hybrid post-quantum algorithm ssh-mldsa44-ed25519; keys created with earlier experimental support must be regenerated or removed.
Article Details
- Event Type
- Security-focused software release
- Impact
- OpenSSH 10.6 disables the LZ77 dictionary coder to reduce cross-channel attacks and includes fixes for username handling, credential persistence, path validation, and certificate expiry times. It also enables the hybrid post-quantum signature algorithm ssh-mldsa44-ed25519; keys made with earlier experimental support must be regenerated or removed.