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VulnerabilityAwaiting classification

CVE-2026-64067

CRITICAL · 9.8 CVSS v3.1 Published 2026-07-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 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 missing barriers when accessing stream->subrequests locklessly The list of subrequests attached to stream->subrequests is accessed without locks by netfs_collect_read_results() and netfs_collect_write_results(), and then they access subreq->flags without taking a barrier after getting the subreq pointer from the list. Relatedly, the functions that build the list don't use any sort of write barrier when constructing the list to make sure that the NETFS_SREQ_IN_PROGRESS flag is perceived to be set first if no lock is taken. Fix this by: (1) Add a new list_add_tail_release() function that uses a release barrier to set the pointer to the new member of the list. (2) Add a new list_first_entry_or_null_acquire() function that uses an acquire barrier to read the pointer to the first member in a list (or return NULL). (3) Use list_add_tail_release() when adding a subreq to ->subrequests. (4) Use list_first_entry_or_null_acquire() when initially accessing the front of the list (when an item is removed, the pointer to the new front iterm is obtained under the same lock).

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 memory ordering vulnerability in the Linux kernel's netfs (network filesystem) subsystem where missing memory barriers during list access in netfs_collect_read_results() and netfs_collect_write_results() could lead to data races. Without proper acquire/release barriers, the NETFS_SREQ_IN_PROGRESS flag may not be perceived as set before accessing subreq->flags, potentially causing incorrect behavior or state confusion.

MitigationApply the upstream kernel patch which introduces list_add_tail_release() and list_first_entry_or_null_acquire() functions to ensure proper memory ordering when accessing stream->subrequests list locklessly.

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

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. Check kernel version
    Run 'uname -r' to get the running kernel version. Compare it to the version that contains the fix for this CVE (typically kernel 6.x series with the netfs memory barrier patches).
    Affected if Running a kernel version prior to the patched version that includes list_add_tail_release() and list_first_entry_or_null_acquire() functions.
  2. Verify netfs subsystem is compiled in
    Check if CONFIG_NETFS_SUPPORT is enabled in the kernel config: 'grep CONFIG_NETFS_SUPPORT /boot/config-$(uname -r)' or check /proc/config.gz if available.
    Affected if The netfs support module (CONFIG_NETFS_SUPPORT) is built into the kernel or as a loadable module.
  3. Identify network filesystems using netfs
    Check loaded modules or running services that use network filesystems: 'lsmod | grep -E "9p|ceph|fscache"' and 'mount | grep -E "9p|ceph"'.
    Affected if Any network filesystem client (such as 9P, Ceph-based filesystems) that relies on the netfs infrastructure is actively mounted or loaded.
  4. Check for concurrent subrequest access patterns
    If using a network filesystem, inspect running processes accessing those mounts and check for concurrent read/write operations that could trigger the race condition in netfs_collect_read_results or netfs_collect_write_results.
    Affected if Multiple threads or processes are simultaneously performing I/O operations on mounted network filesystem paths, causing concurrent access to the subrequest lists.

A system is affected if it runs a kernel version lacking the netfs memory barrier fix, has CONFIG_NETFS_SUPPORT enabled, and actively uses a network filesystem that triggers the vulnerable list traversal code paths.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the upstream kernel patch which introduces list_add_tail_release() and list_first_entry_or_null_acquire() functions to ensure proper memory ordering when accessing stream->subrequests list locklessly.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,100
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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-2026-64067 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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