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CVE Record

CVE-2025-39929: smb: client: fix smbdirect_recv_io leak in smbd_negotiate() error path

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix smbdirect_recv_io leak in smbd_negotiate() error path During tests of another unrelated patch I was able to trigger this error: Objects remaining on __kmem_cache_shutdown()

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel SMB client bug involving a memory or object leak during an SMB Direct negotiation error path. The public record does not provide CVSS, CWE, or detailed impact. Treat it as a kernel maintenance exposure for systems using Linux SMB client functionality, especially where vendor advisories identify affected builds.

Executive priority

Moderate operational priority until vendor impact clarifies. There is no sourced evidence of active exploitation or rated severity, but kernel SMB client bugs can affect reliability in enterprise file-access environments.

Technical view

The fix addresses a smbdirect_recv_io leak in smbd_negotiate() when negotiation fails. The CVE record names Linux kernel versions and stable kernel commits, but does not describe privilege impact, remote triggerability, or exploitability. The issue is resolved by upstream stable commits referenced by the CVE.

Likely exposure

Exposure is most plausible on Linux systems with affected kernel builds that use the SMB client path, particularly SMB Direct-related functionality. The bundle also references a Siemens advisory, but no Siemens product impact details are included here.

Exploitation context

The source bundle does not show CISA KEV listing, active exploitation, public exploit availability, or weaponized details. The description says the leak was triggered during testing of another patch, not observed in attacks.

Researcher notes

Evidence is limited to the CVE description, Linux stable commit references, affected-version metadata, and a Siemens advisory link. No CVSS, CWE, detailed root cause, proof of exploitability, or product-specific Siemens impact is provided in the bundle.

Mitigation direction

  • Identify Linux kernel versions deployed on SMB client systems.
  • Prioritize kernels matching the affected versions listed in the CVE record.
  • Apply vendor kernel updates containing the referenced stable commits.
  • Review Siemens SSA-082556 if Siemens products are in scope.
  • If no vendor update exists, follow vendor guidance for interim handling.

Validation and detection

  • Inventory Linux hosts that mount or access SMB shares.
  • Compare running kernel versions against the CVE affected-version data.
  • Check vendor advisories for backported fixes, not only upstream version numbers.
  • Confirm installed kernel packages include the relevant stable fix commits.
  • Monitor for abnormal kernel memory behavior on SMB client workloads.
Prepared
Confidence
medium
Sources
10

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-2025-39929 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
1ADP providers
9Source 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.

ADP provider summaries

siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxf198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299, f198186aa9bbd60fae7a2061f4feec614d880299unaffected
LinuxLinux4.16, 0, 5.10.259, 5.15.210, 6.1.154, 6.6.108, 6.12.49, 6.16.9, 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.