Windows Server for NFS: out-of-bounds read allows remote code execution against the NFS server

Impact

An out-of-bounds read in the Windows Server for NFS role lets an unauthenticated attacker over the network execute code on the file server. Where a fleet mounts datasets or checkpoints from a Windows NFS export, compromise of that server means the training data and model artifacts every GPU node reads are attacker-controlled, and the file server sits on the same storage network as the nodes. The affected list is limited to older branches (Windows Server 2012, 2012 R2, 2016 and the matching Windows 10 builds). Microsoft's vector records UI:R, so some interaction is a factor; the MSRC entry is the only public detail and no exploit specifics are published.

Who can reach it

Network access to the NFS service on a host with the Server for NFS role enabled. No authentication required per the vector; the vector does record a user-interaction requirement that Microsoft does not elaborate on. Hosts without the NFS role installed are not exposed.

What to do

Apply the October 2026 Microsoft security update for the affected Windows Server build. The patch requires a reboot of the file server, which interrupts every client mount - schedule it against jobs that have the export mounted, or fail over to a second server first. Where the Server for NFS role is not actually used, removing the role removes the exposure without a patch cycle.

References

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