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CVE Record

CVE-2025-38393: NFSv4/pNFS: Fix a race to wake on NFS_LAYOUT_DRAIN

In the Linux kernel, the following vulnerability has been resolved: NFSv4/pNFS: Fix a race to wake on NFS_LAYOUT_DRAIN We found a few different systems hung up in writeback waiting on the same page lock, and one task waiting on the NFS_LAYOUT_DRAIN bit in pnfs_update_layout(), however the pnfs_layout_hdr's plh_outstanding count was zero. It seems most likely that this is another race between the waiter and waker similar to commit ed0172af5d6f ("SUNRPC: Fix a race to wake a sync task"). Fix it up by applying the advised barrier.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel race in NFSv4/pNFS can leave writeback tasks permanently waiting, causing affected systems or storage workloads to hang. The documented impact is loss of availability, not data theft or modification. Systems using pNFS for important shared storage deserve expedited assessment and kernel remediation.

Executive priority

Treat this as a high-priority availability issue for critical pNFS environments, but not as evidence of an active breach. Expedite vendor-confirmed kernel updates where hangs could disrupt production, storage, or industrial operations. Lower priority is reasonable for systems confirmed not to use NFSv4/pNFS.

Technical view

A missed wake-up race can occur while pnfs_update_layout() waits on NFS_LAYOUT_DRAIN, even after plh_outstanding reaches zero. Multiple tasks may then remain blocked on the same page lock during writeback. The upstream correction applies a memory barrier to coordinate the waiter and waker. CVSS 3.1 is 7.5, reflecting network-reachable availability impact.

Likely exposure

Exposure is most likely on affected Linux systems actively using NFSv4/pNFS, particularly write-intensive clients. The supplied version records identify several affected kernel lines, but their flattened presentation is insufficient for reliable package-level decisions. Distribution and appliance advisories should determine whether each installed kernel contains the fix.

Exploitation context

The bundle does not establish active exploitation, and the CVE is not identified as KEV. Although the CVSS vector rates attack complexity low and requires no privileges or user interaction, the supplied description documents observed system hangs rather than a demonstrated remote attack method. Treat exploitability details as incomplete.

Researcher notes

The evidence supports a concurrency defect involving waiter/waker ordering, NFS_LAYOUT_DRAIN, and a zero plh_outstanding count. The fix is represented by multiple stable-kernel commits applying the advised barrier. No confidentiality or integrity impact, public proof of exploitation, reliable trigger conditions, or CWE classification is supplied.

Mitigation direction

  • Apply a vendor-supported kernel update that includes the referenced upstream race-condition fix.
  • Review Debian or appliance-vendor advisories before selecting package versions.
  • Prioritize NFSv4/pNFS clients supporting availability-critical storage workloads.
  • Use vendor guidance if immediate kernel replacement is operationally unsafe.

Validation and detection

  • Inventory running kernel versions and identify systems using NFSv4/pNFS mounts.
  • Confirm installed package changelogs or vendor advisories explicitly address CVE-2025-38393.
  • After updating, reboot where required and verify the fixed kernel is running.
  • Monitor for stalled writeback, page-lock waits, and tasks waiting on NFS_LAYOUT_DRAIN.
Prepared
Confidence
high
Sources
12

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

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CVE-2025-38393 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
3Timeline events
2ADP providers
11Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2025-38393Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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.

ADP provider summaries

CVECVE Program Container
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux8acc3e228e1c90bd410f73597a4549e0409f22d6, ec23a86e060cbe30b62eb2955adc97c92d80cc4c, 880265c77ac415090090d1fe72a188fee71cb458, 880265c77ac415090090d1fe72a188fee71cb458, 880265c77ac415090090d1fe72a188fee71cb458, 880265c77ac415090090d1fe72a188fee71cb458, 880265c77ac415090090d1fe72a188fee71cb458, f133819e24e78f3aaaa00e9fa2b816d5f73fd172, 5.10.124, 5.15.49, 5.18.6unaffected
LinuxLinux5.19, 0, 5.10.240, 5.15.187, 6.1.144, 6.6.97, 6.12.37, 6.15.6, 6.16affected
Weakness

CWE details

No CWE listed

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