522
backdoor in upstream xz/liblzma leading to ssh server compromise
(www.openwall.com)
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
Community icon by Alpár-Etele Méder, licensed under CC BY 3.0
The base runtime pretty much every Flatpak uses includes xz/liblzma, but none of the affected versions are included. You can poke around in a base runtime shell with
flatpak run --command=sh org.freedesktop.Platform//23.08
or similar, and check your installed runtimes withflatpak list --runtime
.23.08 is the current latest version used by most apps on Flathub and includes xz 5.4.6. 22.08 is an older version you might also still have installed and includes xz 5.2.12. They're both pre-backdoor.
It seems there's an issue open on the freedesktop-sdk repo to revert xz to an even earlier version predating the backdoorer's significant involvement in xz, which some other distros are also doing out of an abundance of caution.
So, as far as we know: nothing uses the backdoored version, even if it did use that version it wouldn't be compiled in (since org.freedesktop.Platform isn't built using Deb or RPM packaging and that's one of the conditions), even if it was compiled in it would to our current knowledge only affect sshd, the runtime doesn't include an sshd at all, and they're still being extra cautious anyway.
One caveat: There is an unstable version of the runtime that does have the backdoored version, but that's not used anywhere (I don't believe it's allowed on Flathub since it entirely defeats the point of it).