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Linux KernelOperating system · Linux

CVE-2026-53026

HIGH · 7.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.18.33 / 7.0.10 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available 8 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: NFSD: fix nfs4_file access extra count in nfsd4_add_rdaccess_to_wrdeleg In nfsd4_add_rdaccess_to_wrdeleg, if fp->fi_fds[O_RDONLY] is already set by another thread, __nfs4_file_get_access should not be called to increment the nfs4_file access count since that was already done by the thread that added READ access to the file. The extra fi_access count in nfs4_file can prevent the corresponding nfsd_file from being freed. When stopping nfs-server service, these extra access counts trigger a BUG in kmem_cache_destroy() that shows nfsd_file object remaining on __kmem_cache_shutdown. This problem can be reproduced by running the Git project's test suite over NFS.

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 race condition in the Linux kernel's NFSD causes multiple threads to incorrectly increment the nfs4_file access count when adding READ access to a file that already has READ access set by another thread. This extra fi_access count prevents nfsd_file objects from being freed, triggering a BUG in kmem_cache_destroy() during NFS server shutdown.

MitigationApply the kernel patch that prevents calling __nfs4_file_get_access when fp->fi_fds[O_RDONLY] is already set; upgrade the Linux kernel to the 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:>= 6.18.4, < 6.18.33>= 6.19.1, < 7.0.10= 6.19

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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' or 'cat /proc/version' to get the running kernel version
    Affected if The kernel version falls within >= 6.18.4 and < 6.18.33, OR = 6.19, OR >= 6.19.1 and < 7.0.10
  2. Verify NFSD kernel module is loaded
    Run 'lsmod | grep nfsd' to check if the nfsd module is loaded into the kernel
    Affected if The nfsd module is currently loaded in memory
  3. Check if nfsd service is active
    Run 'systemctl status nfs-server' or 'service nfs-server status' depending on your init system, or check for nfsd processes with 'ps aux | grep nfsd'
    Affected if The nfsd server daemon is currently running
  4. Identify exported NFS shares
    Run 'exportfs -v' or check /var/lib/nfs/v4recovery for exported directories to see what is being served
    Affected if The NFS server has one or more directories exported and available to clients
  5. Observe nfsd shutdown behavior
    Stop the nfsd service and monitor kernel logs with 'dmesg' or check /var/log/messages for 'BUG' or 'kmem_cache_destroy' errors related to nfsd_file
    Affected if During nfsd shutdown, the kernel reports a BUG in kmem_cache_destroy() or nfsd_file objects fail to be freed

A system is affected if it runs a vulnerable kernel version (within the specified ranges) AND has the NFSD server module loaded or running with exported shares, especially if shutdown reveals reference count issues.

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.

dbcve · scoped
Upgrade available Upgrade to 6.18.33 / 7.0.10 or later
Fixed in 6.18.337.0.10
Vendor patch git.kernel.org →
Interim mitigation

Apply the kernel patch that prevents calling __nfs4_file_get_access when fp->fi_fds[O_RDONLY] is already set; upgrade the Linux kernel to the version containing this fix.

Recommended fix High confidence

6.18.33+ or 7.0.10+ (or any 7.1.x/7.2.x stable release)

  1. Upgrade Linux kernel to version 6.18.33 or later for the 6.18.x stable branch
  2. Alternatively, upgrade to version 7.0.10 or later for the 7.0.x stable branch
  3. Alternatively, upgrade to any kernel version >= 7.1.0 which contains the fix
  4. After upgrade, reboot the system to load the fixed kernel
  5. Verify the kernel version post-boot with: uname -r
Caveat Kernel upgrades may require rebuilding out-of-tree kernel modules; ensure driver compatibility before upgrading production systems

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation3.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,480
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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-2026-53026 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data