CVE-2026-64159 Linux CVE debrief

Who should care

Users of Linux kernel with uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio should be aware of this vulnerability and take necessary actions to protect their systems.

Technical summary

The Linux kernel was vulnerable to an issue in the netfs module. A fix was applied to correctly update the zero point in netfs_release_folio() when there is uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio. The update needs to limit zero_point to remote_i_size, not i_size as i_size is a local phenomenon reflecting updates made locally to the pagecache, not stuff written to the server. remote_i_size tracks the server's i_size. This fix prevents read-gaps on folio failing with a short read.

Defensive priority

Medium

Recommended defensive actions

• Apply the fix to update the zero point in netfs_release_folio()
• Limit zero_point to remote_i_size, not i_size
• Monitor for uncommitted data in the pagecache beyond the folio being released but the on-server EOF is in this folio
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-19T16:17:57.913Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the official advisory.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.