[paolomainardi]

I am wondering if reinstalling the entire Archlinux installation would be a wise choice.

[sebiw]

Arch Linux uses a native/unpatched version of OpenSSH without dependency on libsystemd and thus without dependency on xz-utils, resulting in no exploitable code path. This means that at least the currently talked about vulnerability/exploit via SSH did presumably not work on Arch. Disclaimer: This is my understanding of the currently circulating facts. Additional fallout might be possible, as the reverse engineering of the backdoor is ongoing.

[Deathcrow]

This is only correct if the sshd backdoor is the only malicious code introduced into the library.

[pas]

there are other ways for liblzma to get into ssh (via PAM and libselinux)

[Phelinofist]

Just to extend the sibling comment with an excerpt of the Arch announce mail regarding the backdoor:

  >From the upstream report [1]:
  
  > openssh does not directly use liblzma. However debian and several other
  distributions patch openssh to support systemd notification, and libsystemd
  does depend on lzma.
  
  Arch does not directly link openssh to liblzma, and thus this attack vector is not possible. You can confirm this by issuing the following command:
   
   ```
   ldd "$(command -v sshd)"
   ```
   
  However, out of an abundance of caution, we advise users to remove the malicious code from their system by upgrading either way. This is because other yet-to-be discovered methods to exploit the backdoor could exist.