Linux Kernel EUVD-2026-26367

Upgrade to patched Linux kernel versions: 6.6.128 or later for 6.6.x series, 6.12.75 or later for 6.12.x series, 6.18.16 or later for 6.18.x series, 6.19.6 or later for 6.19.x series, or upgrade to mainline 7.0 when released. Upstream fixes are confirmed in git commits c854ab481ece (6.6 stable), 1d731e512134 (6.12 stable), 7c9ce68192ee (6.18 stable), c99e160938b6 (6.19 stable), and 14f66f446463 (mainline), available at git.kernel.org/stable. For systems requiring temporary mitigation before patching, consider unmounting CIFS shares if business operations permit, though this eliminates functionality rather than reducing risk. Alternatively, restrict local user access to systems with active CIFS mounts using stricter authentication policies and user account controls, recognizing this reduces likelihood but doesn't eliminate the vulnerability. Note that disabling CIFS kernel module (blacklisting cifs.ko) prevents exploitation but also breaks all SMB/CIFS mounting functionality. Network-level controls are ineffective since this is a local privilege issue, not a network-based attack. No performance or stability side effects expected from kernel patches, but test in non-production environments first per standard kernel update procedures.