Valve ships SteamOS 3.9.5 with Plasma 6.7.3 and eMudhra cert revocation
The stable update also cuts Steam Deck idle power draw when no audio is playing and fixes bugs affecting Steam Machine performance.
Valve released the stable version 3.9.5 of SteamOS on October 26, 2026, according to gamespark.jp. The update moves the desktop mode environment from KDE Plasma 6.4.3 to Plasma 6.7.3 and revokes a compromised eMudhra CA certificate.
On the Steam Deck, Valve says the build improves idle power consumption when no audio is playing. The patch notes also list fixes for a range of bugs, including some that affected Steam Machine performance.
Valve describes the certificate revocation as a security and stability update. The change follows an incident involving the Indian certificate issuer eMudhra, whose private keys for eight intermediate certificates were compromised, temporarily making it easier for malicious actors to impersonate secure sites.
Browsers including Firefox have blocked eMudhra's digital certificates since that incident, and on October 22, 2026, eMudhra announced its withdrawal from the global SSL/TLS certificate business.
Quick answers
What changed in SteamOS 3.9.5?
Desktop mode moves from KDE Plasma 6.4.3 to Plasma 6.7.3, idle power use on Steam Deck improves when no audio is playing, bug fixes include Steam Machine performance issues, and a compromised eMudhra CA certificate was revoked.
Why did SteamOS revoke an eMudhra certificate?
Valve lists it as a security and stability update after eMudhra's intermediate certificate keys were compromised.