OpenSSH 10.6 / 10.6p1 was released on 6 October 2026 with a batch of security fixes for both the ssh client and the sshd server. The headline change disables the LZ77 dictionary coder in compression: researchers Fabian Bäumer and Marcus Brinkmann showed in "Crossing the Streams" that, when compression is on, all channels in one SSH connection share one compression dictionary, so an attacker who can feed chosen text into one channel and watch ciphertext lengths can recover secrets carried in another channel.

Compression still works but is less effective. The sftp client now validates paths returned by a server more strictly, so a malicious server can no longer steer a recursive download into writing outside its target folder (reported by Junghoon Cho). The ssh client now refuses destination usernames containing $ or \ on the command line, because usernames from untrusted sources could reach a shell through ProxyCommand or Match exec (reported by KeenLab Tencent); usernames set with the User directive in config files are not restricted.

Other fixes cover GSSAPI credentials from a failed attempt persisting into a later login, the authorized_keys "restrict" keyword not applying to tunnel forwarding, compressed packets inflating past the size limit, and a root-privileged session process on old platforms without file-descriptor passing (GatewayPorts and StreamLocalForwarding are now forced off there).

The OpenSSH team says it is getting many AI-assisted bug reports, has seen AI-found bugs rediscovered independently, and will ship releases more often.

The release notes assign no CVE numbers or CVSS scores, but MITRE published CVE records for the fixes on 6 and 7 October.

UPDATE 15 October: Red Hat tracked the root-retaining session-process issue as CVE-2026-110929 (Important, draft CVSS 3.1 8.1); it has since rejected that ID as a duplicate of CVE-2026-106589, which it rates Low (draft CVSS 3.1 2.9). An authenticated user on an affected build can act as root, including making privileged socket connections and binding forwards to low-numbered ports.

Red Hat says Red Hat Enterprise Linux, and Linux generally, is not affected because the post-authentication process drops to the logged-in user there. The flaw applies to QNX 6, SCO OpenServer 5 and OpenSSH builds made with --disable-fd-passing, which should upgrade to 10.6.

Primary: OpenSSH 10.6 release notes; wire: Cyber Security News (7 Oct).

Correction (22 Oct 2026): this card gave the root-retaining session-process flaw as CVE-2026-110929 with Red Hat's draft score of 8.1 (Important) and said the 10.6 fixes had no CVEs. Red Hat has rejected CVE-2026-110929 as a duplicate of CVE-2026-106589, which it rates Low (draft CVSS 3.1 2.9), and MITRE published CVE records for the 10.6 fixes on 6 and 7 October. (source: Red Hat CVE database)