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CVE Record

CVE-2025-38567: nfsd: avoid ref leak in nfsd_open_local_fh()

In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid ref leak in nfsd_open_local_fh() If two calls to nfsd_open_local_fh() race and both successfully call nfsd_file_acquire_local(), they will both get an extra reference to the net to accompany the file reference stored in *pnf. One of them will fail to store (using xchg()) the file reference in *pnf and will drop that reference but WON'T drop the accompanying reference to the net. This leak means that when the nfs server is shut down it will hang in nfsd_shutdown_net() waiting for &nn->nfsd_net_free_done. This patch adds the missing nfsd_net_put().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can make an NFS server hang during shutdown after a race leaks a reference. The known impact is operational availability and maintenance disruption, not data theft or code execution. Public severity data is missing, so urgency depends on whether the organization runs affected Linux kernels with NFSD enabled.

Executive priority

Handle as a targeted availability risk for NFS infrastructure. Prioritize systems where NFS service uptime or maintenance windows are business-critical. Do not treat it as confirmed actively exploited based on the provided evidence.

Technical view

The flaw is a race in nfsd_open_local_fh(). Competing calls can both acquire a local file and related network reference. The losing xchg() path drops the file reference but misses nfsd_net_put(), leaking the net reference and causing nfsd_shutdown_net() to wait indefinitely.

Likely exposure

Exposure appears limited to Linux systems running affected kernel versions with the in-kernel NFS server path in use. The source lists affected Linux versions including 6.16, 6.15.10, 6.16.1, and 6.17, but distro backport status is not provided.

Exploitation context

The bundle does not show CISA KEV listing, active exploitation, exploit availability, or an attack vector. The described condition is a concurrency bug in NFSD that can lead to shutdown hang. Treat exploitation details as unknown unless vendor advisories add more evidence.

Researcher notes

Evidence supports a reference leak in a specific NFSD race path. No CVSS, CWE, exploit status, or distro-specific fixed versions are included. The patch-level remedy is the added nfsd_net_put(), but operational remediation should follow kernel or distribution guidance.

Mitigation direction

  • Apply kernel updates that include the referenced stable fixes.
  • Check Linux distribution advisories for backported package status.
  • Prioritize NFS server hosts before general Linux endpoints.
  • If NFSD is unnecessary, disable it using existing hardening procedures.
  • Plan maintenance carefully because affected servers may hang during NFS shutdown.

Validation and detection

  • Inventory Linux kernel versions on NFS server hosts.
  • Confirm whether NFSD or NFS server services are enabled.
  • Map installed kernels against vendor fixed package guidance.
  • Check whether referenced stable commits are included in deployed kernels.
  • Review shutdown or maintenance logs for NFSD hang symptoms.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
4Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux986a21ace186433e0397a59491646edad8c8d636, e6f7e1487ab528a6c653bd0d42812ff2942846cd, e6f7e1487ab528a6c653bd0d42812ff2942846cd, 6.15.3unaffected
LinuxLinux6.16, 0, 6.15.10, 6.16.1, 6.17affected
Weakness

CWE details

No CWE listed

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