SteamOS 3.9.5 ships Linux 7.2 and KDE Plasma 6.7

Valve has released SteamOS 3.9.5, the first stable build in the SteamOS 3.9 series, to all users. It shipped on Friday, October 23, 2026. The update moves the system behind the Steam Deck to the Linux 7.2 kernel and KDE Plasma 6.7.3, a big step up from Plasma 6.4.3.

SteamOS is Valve's own Linux-based operating system. On the Steam Deck handheld it runs Game Mode, the console-style screen, and a Desktop Mode that works like a regular Linux PC.

GamingOnLinux says Valve made 3.9.5 "stable for all users across all supported systems." Phoronix notes that it brings features tested earlier in preview builds. GamerHeadlines calls it the first stable release since SteamOS 3.8.

What changed in SteamOS 3.9.5

The three reports agree on the main changes:

Area	Change in 3.9.5
Linux kernel	Rebased on Linux 7.2
Desktop Mode	KDE Plasma 6.4.3 to 6.7.3
Base system	Updated Arch Linux base
Wi-Fi	wpa_supplicant is the default, with fast reconnect after sleep
Power	Steam Deck uses less power at idle when no audio plays
Hibernation	Preliminary support, hidden from Game Mode
Accessories	Support for the Steam Frame wireless adapter
Certificates	Certificates from the eMudhra authority revoked
Naming	"steamos-" scripts and packages renamed to "holo-"

Phoronix also lists an updated bootloader and better support for running SteamOS as a virtual machine guest.

A newer kernel and desktop

The kernel is the core of an operating system. It talks to the chips, the storage and the controllers. GamingOnLinux says the move to Linux 7.2 is meant to support more hardware.

Plasma is the desktop you see in Desktop Mode: the windows, panels and settings. The jump from 6.4.3 to 6.7.3 spans three feature releases, and GamingOnLinux links the notes for Plasma 6.5, 6.6 and 6.7.

SteamOS still trails the newest upstream versions. Linux 7.3 came out earlier this month, as Tech AI Wire reported on October 19. KDE also shipped Plasma 6.8 on October 15, the release that dropped the X11 session. So 3.9.5 brings Steam Deck owners much closer to current Linux, but not all the way.

Wi-Fi, sleep and hibernation

Wi-Fi gets a new default program. SteamOS now uses wpa_supplicant, a long-standing Linux Wi-Fi tool, in place of iwd. According to GamerHeadlines, fast reconnect after waking from sleep used to work only with iwd. Now wpa_supplicant has it too.

Hibernation saves a whole session to storage so the device can power off fully and resume later. In 3.9.5 that support is only preliminary. GamerHeadlines says it is not exposed in Game Mode. On the Steam Deck it stays disabled because of an outstanding driver bug, and no source gives a date for a fix.

The Steam Deck should also draw less power when it sits idle with no audio playing. GamerHeadlines says Valve gave no percentage for the saving.

Security fixes and renamed tools

GamingOnLinux reports that certificates from the eMudhra certificate authority were compromised, and Valve revoked them in this release. A certificate authority vouches for the identity of websites and servers. Once its certificates are revoked, the system stops trusting connections that rely on them.

The update also renames scripts and packages that began with "steamos-" so they now begin with "holo-".

What this means for developers

Game developers who test on the Steam Deck should run their checks again after the update. A kernel jump to Linux 7.2 can change how games behave. Compare frame rates, suspend and resume, and controller input before and after.

If you ship a Linux app that people use in Desktop Mode, test it under Plasma 6.7.3. Tray icons, file dialogs and window rules are the usual places a desktop update shows up.

Search your own scripts and setup guides for commands that start with "steamos-". The rename to "holo-" can break anything that calls the old names.

If a tool on your Deck talks to a server whose certificate comes from eMudhra, expect that connection to fail now. That is the revocation working as intended, not a bug to work around.

Do not plan around hibernation on the Steam Deck yet. It is preliminary, hidden from Game Mode and switched off on that device. Watch the next 3.9 point releases for the driver fix.