#1150271 openssh-sftp-server: sftp-server fails silently with return code 11 on arm64 (Raspberry Pi4)

Package:
openssh-sftp-server
Source:
openssh-sftp-server
Description:
secure shell (SSH) sftp server module, for SFTP access from remote machines
Submitter:
Jean-Luc Dalous
Date:
2026-10-08 10:17:01 UTC
Severity:
normal
#1150271#5
Date:
2026-10-07 20:14:15 UTC
From:
To:
Steps to reproduce:
printf '3\n\n1\n\n' | /usr/lib/openssh/sftp-server; echo $? → rc=11, no output at all.
No error is logged by sshd or the kernel. Switching to Subsystem sftp internal-sftp in sshd_config fully works around the issue, which suggests a problem in the external binary (possibly its seccomp sandbox on arm64).
#1150271#10
Date:
2026-10-08 10:15:41 UTC
From:
To:
This isn't a valid reproducer, because that exit code is expected in
this case due to the input not being a well-formed SSH protocol message.
If you add the -e option, you should see something like:

   $ printf '3\n\n1\n\n' | /usr/lib/openssh/sftp-server -e
   bad message from 62.31.171.222 local user cjwatson

I assume that you derived this reproducer from something more
complicated.  Could you go back a few steps?