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Linux KernelOperating system · Linux

CVE-2026-64216

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-24
Fix available
A fix is available. Upgrade to 6.18.34 / 7.0.11 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix potential UAF in netfs_unlock_abandoned_read_pages() netfs_unlock_abandoned_read_pages(rreq) accesses the index of the folios it is wanting to unlock and compares that to rreq->no_unlock_folio so that it doesn't unlock a folio being read for netfs_perform_write() or netfs_write_begin(). However, given that netfs_unlock_abandoned_read_pages() is called _after_ NETFS_RREQ_IN_PROGRESS is cleared, the one folio that it's not allowed to dereference is the one specified by ->no_unlock_folio as ownership immediately reverts to the caller. Fix this by storing the folio pointer instead and using that rather than the index. Also fix netfs_unlock_read_folio() where the same applies.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A Use-After-Free (UAF) vulnerability exists in the Linux kernel's netfs (network filesystem) subsystem. The function netfs_unlock_abandoned_read_pages() attempts to dereference the index stored in rreq->no_unlock_folio after NETFS_RREQ_IN_PROGRESS has been cleared, at which point ownership of that folio reverts to the caller. This creates a UAF condition where the kernel accesses memory it no longer owns. The fix involves storing and using the folio pointer directly rather than dereferencing through the index.

MitigationThis kernel vulnerability requires a code fix to store the folio pointer instead of the index before ownership transfer. Apply the upstream Linux kernel patch which changes netfs_unlock_abandoned_read_pages() and netfs_unlock_read_folio() to use folio pointers. Update to a kernel version containing this fix.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.12, < 6.18.34>= 6.19, < 7.0.11= 7.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify kernel version
    Run 'uname -r' or check /proc/version to get the running kernel version
    Affected if The kernel version is within the affected range and predates the upstream fix commit for this UAF vulnerability
  2. Check if netfs module is loaded
    Run 'lsmod | grep netfs' or check /proc/modules to see if the netfs module is currently loaded
    Affected if The netfs module is loaded and the kernel version is unpatched for this vulnerability
  3. Verify netfs support in kernel
    Check kernel config: 'cat /boot/config-$(uname -r) | grep -i netfs' or check /proc/config.gz if available
    Affected if CONFIG_NETFS_SUPPORT is enabled (y or m) in the kernel configuration and the kernel version lacks the fix
  4. Identify active network filesystems using netfs
    Run 'mount | grep -E "nfs|ceph|9p"' or check 'cat /proc/mounts' for mounted network filesystems
    Affected if A network filesystem (NFS, Ceph, 9P) is actively mounted and the underlying kernel is vulnerable
  5. Inspect netfs folio handling code
    Examine the source file fs/netfs/buffered_read.c for the netfs_unlock_abandoned_read_pages function - check if it still uses folio index instead of folio pointer
    Affected if The source code shows index-based comparison instead of pointer-based storage in the affected functions

The system is affected if the running kernel version predates the fix and the netfs subsystem (used by network filesystems) is enabled or actively in use.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to 6.18.34 / 7.0.11 or later
Fixed in 6.18.347.0.11
Interim mitigation

This kernel vulnerability requires a code fix to store the folio pointer instead of the index before ownership transfer. Apply the upstream Linux kernel patch which changes netfs_unlock_abandoned_read_pages() and netfs_unlock_read_folio() to use folio pointers. Update to a kernel version containing this fix.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-64216 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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