[Pkg-openssl-devel] Bug#941665: libssl1.1: Breaks ssh privsep_preauth in some circumstances

[fabien at maintenancia.com]

Package: libssl1.1
Version: 1.1.1d-0+deb10u1
Severity: important

Dear Maintainer,

I upgraded openssl and libssl1.1 to version 1.1.1d-0+deb10u1 (from
1.1.1c-1).

After that, I wasn't able to log in to this machine through ssh. Any
attempt failed with the following error (in /v/l/auth.log):

   sshd[****]: Accepted publickey for ***** from ***** port ***** ssh2: RSA SHA256:*****
   sshd[****]: fatal: privsep_preauth: preauth child terminated by signal 31

Error on the client occured after key exchange or password input and was:

  Write failed: Broken pipe

After different attempts having no effect, I downgraded openssl and
libssl1.1 to version 1.1.1c-1. And it fixed the issue.

It might be related to the fact that my system is a VPS running on an
old kernel (3.16.0-4).

-- System Information:
Debian Release: 10.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)