ssh_dispatch_run_fatal: incorrect signature with mlkem768x25519-sha256

[Damien Miller]

On Tue, 28 Oct 2025, Christian Kujau wrote:

> Hello list,
> 
> I have this PowerBook G4 with OpenBSD 7.6 (macppc, OpenSSH_9.9, LibreSSL 
> 4.0.0) installed but haven't used it in a while. Switched it on and wanted 
> to SSH from my Macbook (M2, with macOS 26 installed, OpenSSH_10.0p2, 
> LibreSSL 3.3.6) to the Powerbook but:
> 
>  $ ssh 192.168.178.62
>  ssh_dispatch_run_fatal: Connection to 192.168.178.62 port 22: incorrect signature

This is probably fixed by this, which landed after 9.9:

commit cf3e48ee8ba1beeccddd2f203b558fa102be67a2
Author: djm at openbsd.org <djm at openbsd.org>
Date:   Sun Oct 27 02:06:01 2024 +0000

    upstream: fix ML-KEM768x25519 KEX on big-endian systems; spotted by
    
    jsg@ feedback/ok deraadt@
    
    OpenBSD-Commit-ID: 26d81a430811672bc762687166986cad40d28cc0