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CVE Record

CVE-2025-38561: ksmbd: fix Preauh_HashValue race condition

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix Preauh_HashValue race condition If client send multiple session setup requests to ksmbd, Preauh_HashValue race condition could happen. There is no need to free sess->Preauh_HashValue at session setup phase. It can be freed together with session at connection termination phase.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A race condition in the Linux kernel’s ksmbd SMB server can occur when multiple session-setup requests overlap. The supplied CVSS rating is 9.8, reflecting potentially severe confidentiality, integrity, and availability impact. Exposure requires ksmbd to be present, enabled, and reachable. The supplied evidence does not confirm real-world exploitation.

Executive priority

Treat reachable ksmbd servers as an urgent patching priority because the supplied rating is critical and authentication is not required. Internet-facing or broadly accessible SMB services should be addressed first. Systems without ksmbd enabled are unlikely to expose this specific flaw. Confirm vendor backports before declaring systems vulnerable or remediated.

Technical view

Concurrent ksmbd session-setup requests can race around sess->Preauth_HashValue lifecycle handling. The kernel fix avoids freeing this value during session setup and instead releases it with the session when the connection terminates. The record classifies the flaw as CWE-362 and network-accessible without privileges or user interaction, although demonstrated impact is not detailed in the supplied description.

Likely exposure

Prioritize Linux systems running an affected kernel with ksmbd enabled and SMB reachable from untrusted networks. The supplied version list includes 5.15 and several 6.x releases, but does not clearly express complete range boundaries. Distribution backports may change exposure, so verify package-specific status and fix inclusion rather than relying only on version strings.

Exploitation context

The supplied record is not in CISA KEV, and no provided evidence establishes active exploitation. The documented trigger involves overlapping session-setup requests. The CVSS vector indicates remote, unauthenticated, low-complexity reachability, but the bundle does not document a public proof of concept, observed attacks, or reliably demonstrated outcomes.

Researcher notes

The source bundle supports a Preauth_HashValue lifetime race and a fix deferring release until connection termination. It does not establish whether exploitation yields memory corruption, code execution, information disclosure, or only denial of service. The listed affected versions are ambiguous and include duplicated commit data, so use kernel or distribution fix provenance for precise assessment.

Mitigation direction

  • Upgrade to a vendor-supported kernel containing the applicable stable fix.
  • Check distribution security guidance for backported fixes and corrected package versions.
  • Restrict SMB access to trusted networks while remediation is pending.
  • Disable ksmbd where it is unnecessary and operationally safe.

Validation and detection

  • Inventory systems where ksmbd is installed, loaded, or configured to start.
  • Confirm whether SMB endpoints are reachable from untrusted or internet-facing networks.
  • Compare each running kernel against distribution advisories and applicable stable fix commits.
  • After updating, verify the running kernel includes the fix and ksmbd services restarted appropriately.
Prepared
Confidence
medium
Sources
8

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-362: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2025-38561 mapping review

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/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.

2CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

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

CVSS vector scores

2 official scores

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
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Linux
8.5CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H1.86CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2025-38561Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/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

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cfunaffected
LinuxLinux5.15, 0, 6.1.148, 6.6.102, 6.12.42, 6.15.10, 6.16.1, 6.17affected
Weakness

CWE details

CWE-362

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

CWE-362 · source CWE mapping

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs