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CVE Record

CVE-2025-39825: smb: client: fix race with concurrent opens in rename(2)

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix race with concurrent opens in rename(2) Besides sending the rename request to the server, the rename process also involves closing any deferred close, waiting for outstanding I/O to complete as well as marking all existing open handles as deleted to prevent them from deferring closes, which increases the race window for potential concurrent opens on the target file. Fix this by unhashing the dentry in advance to prevent any concurrent opens on the target.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-39825 is a Linux kernel SMB client race condition during file rename operations. The public record does not provide CVSS severity or detailed impact. Organizations most exposed are those using Linux systems to mount SMB/CIFS shares. Treat this as a kernel maintenance issue, prioritized higher where SMB client file operations are business-critical.

Executive priority

Medium operational priority where Linux systems rely on SMB shares; otherwise standard patch-cycle priority. There is no sourced evidence of active exploitation or a rated severity, but kernel race fixes can affect reliability and security boundaries in shared-file workflows.

Technical view

The Linux SMB client rename(2) path could race with concurrent opens while handling deferred closes, outstanding I/O, and deleted handle marking. The upstream fix unhashes the dentry earlier to prevent concurrent opens on the target. Public sources list affected Linux kernel versions and stable commits, but do not provide CWE, CVSS, or exploitability details.

Likely exposure

Linux hosts, appliances, or products using affected kernels and the SMB/CIFS client are the likely exposure. Systems that do not mount SMB shares are less likely to encounter the vulnerable code path. Debian LTS and Siemens published related advisories, so downstream vendor packaging may matter.

Exploitation context

No active exploitation is indicated by CISA KEV or the provided sources. The issue appears tied to timing-sensitive rename and open activity in the SMB client. Public sources do not describe a practical attack path, required privileges, or security impact beyond the resolved race condition.

Researcher notes

Impact details are sparse. The key code-path clue is the SMB client rename(2) race involving deferred close handling and concurrent opens. Analysis should focus on affected kernel branches, downstream backports, and whether mounted SMB workloads can trigger unsafe state or reliability failures.

Mitigation direction

  • Update affected Linux kernels using distribution or vendor-supported packages.
  • For embedded or appliance systems, follow the vendor advisory and firmware guidance.
  • Prioritize systems that actively mount SMB/CIFS shares.
  • If updates are unavailable, monitor vendor guidance for supported mitigations.
  • Avoid relying on custom workarounds not documented by the vendor.

Validation and detection

  • Inventory Linux kernel versions across servers, endpoints, and appliances.
  • Identify systems using SMB/CIFS client mounts.
  • Check whether installed kernels include the referenced stable fix commits.
  • Review Debian LTS or vendor advisories for package-specific status.
  • Confirm remediation through approved kernel package or firmware version records.
Prepared
Confidence
medium
Sources
9

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.

ATT&CK lookup starting points

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CVE-2025-39825 mapping review

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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
3ADP providers
8Source links

SSVC decision data

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

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
LinuxLinux78c09634f7dc061a3bd09704cdbebb3762a45cdf, 78c09634f7dc061a3bd09704cdbebb3762a45cdf, 78c09634f7dc061a3bd09704cdbebb3762a45cdf, 78c09634f7dc061a3bd09704cdbebb3762a45cdf, 78c09634f7dc061a3bd09704cdbebb3762a45cdfunaffected
LinuxLinux5.13, 0, 6.1.150, 6.6.104, 6.12.45, 6.16.5, 6.17affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.