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CVE Record

CVE-2025-39697: NFS: Fix a race when updating an existing write

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix a race when updating an existing write After nfs_lock_and_join_requests() tests for whether the request is still attached to the mapping, nothing prevents a call to nfs_inode_remove_request() from succeeding until we actually lock the page group. The reason is that whoever called nfs_inode_remove_request() doesn't necessarily have a lock on the page group head. So in order to avoid races, let's take the page group lock earlier in nfs_lock_and_join_requests(), and hold it across the removal of the request in nfs_inode_remove_request().

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race condition in the Linux kernel’s NFS write handling can allow an existing write request to be removed at the wrong time. The supplied CVSS assessment indicates that a locally authenticated, low-privilege attacker could potentially compromise confidentiality, integrity, and availability. Systems using affected kernels and NFS write workloads warrant prompt review.

Executive priority

Treat as a high-priority maintenance issue for NFS-dependent servers, appliances, and multi-user Linux systems. Prioritize exposed or business-critical workloads, but avoid emergency claims unsupported by exploitation evidence. Confirm vendor applicability and schedule tested kernel updates promptly.

Technical view

The flaw occurs between nfs_lock_and_join_requests() confirming that a request remains attached to its mapping and acquiring the page-group lock. During that window, nfs_inode_remove_request() can remove the request. The fix acquires the page-group lock earlier and retains it across request removal, preventing the concurrent state change.

Likely exposure

Exposure is limited to Linux systems running affected kernel builds where the vulnerable NFS write path is reachable. The source bundle lists several affected version identifiers, but their range semantics are unclear. Distribution backports may change whether a particular reported kernel version is vulnerable, so package-level verification is necessary.

Exploitation context

The CVSS vector requires local access and low privileges, with no user interaction. The source bundle does not establish a reliable trigger scenario or practical exploitability. This CVE is not listed as KEV, and the supplied sources provide no evidence of active exploitation or a public exploit.

Researcher notes

The record describes a concurrency flaw in NFS request lifecycle and locking. No CWE is supplied. The listed affected versions are ambiguous and should not be interpreted as clean version ranges. Stable kernel commits demonstrate remediation across branches, but the bundle does not document exploit reliability, triggering conditions, or observed attacks.

Mitigation direction

  • Install the vendor-supported kernel update containing the applicable stable fix.
  • Check distribution or appliance advisories because kernel fixes are frequently backported.
  • Reboot into the updated kernel after installation.
  • Restrict unnecessary local access while affected systems await maintenance.

Validation and detection

  • Inventory running kernel versions on systems using NFS clients or mounts.
  • Confirm the vendor package includes the relevant upstream fix or backport.
  • After rebooting, verify the running kernel matches the updated package.
  • Review system logs for NFS errors, kernel warnings, crashes, or unexplained write anomalies.
Prepared
Confidence
medium
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-2025-39697 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
3ADP providers
12Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2025-39697Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxbd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2a, bd37d6fce184836bd5e7cd90ce40116a4fadaf2aunaffected
LinuxLinux4.14, 0, 5.10.242, 5.15.191, 6.1.150, 6.6.104, 6.12.44, 6.16.4, 6.17affected
Weakness

CWE details

No CWE listed

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