Backdoor Found in XZ Tools Used by Most Linux Distros

"Red Hat warns users to immediately stop using systems running Fedora development and experimental versions because of a backdoor found in the latest XZ Utils data compression tools and libraries," reports Bleeping Computer.

Backdoor Found in XZ Tools Used by Most Linux Distros
  • "Microsoft software engineer Andres Freund discovered the security issue while investigating slow SSH logins on a Linux box running Debian Sid (the rolling development version of the Debian distro)."
  • "The latest versions of the “xz” tools and libraries contain malicious code that appears to be intended to allow unauthorized access. Specifically, this code is present in versions 5.6.0 and 5.6.1 of the libraries."
  • "Fedora Linux 40 users may have received version 5.6.0, depending on the timing of system updates. Fedora Rawhide users may have received version 5.6.0 or 5.6.1. This vulnerability was assigned CVE-2024-3094."
"PLEASE IMMEDIATELY STOP USAGE OF ANY FEDORA RAWHIDE INSTANCES for work or personal activity. Fedora Rawhide will be reverted to xz-5.4.x shortly, and once that is done, Fedora Rawhide instances can safely be redeployed. Note that Fedora Rawhide is the development distribution of Fedora Linux, and serves as the basis for future Fedora Linux builds (in this case, the yet-to-be-released Fedora Linux 41)," writes Red Hat.
  • "At this time the Fedora Linux 40 builds have not been shown to be compromised. We believe the malicious code injection did not take effect in these builds. However, Fedora Linux 40 users should still downgrade to a 5.4 build to be safe. An update that reverts xz to 5.4.x has recently been published and is becoming available to Fedora Linux 40 users through the normal update system. Concerned users can force the update by following the instructions here."
"Under the right circumstances this interference could potentially enable a malicious actor to break sshd authentication and gain unauthorized access to the entire system remotely."

Bleeping Computer Article / Archive
Red Hat Article / Archive discussion