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CVE Record

CVE-2025-21947: ksmbd: fix type confusion via race condition when using ipc_msg_send_request

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix type confusion via race condition when using ipc_msg_send_request req->handle is allocated using ksmbd_acquire_id(&ipc_ida), based on ida_alloc. req->handle from ksmbd_ipc_login_request and FSCTL_PIPE_TRANSCEIVE ioctl can be same and it could lead to type confusion between messages, resulting in access to unexpected parts of memory after an incorrect delivery. ksmbd check type of ipc response but missing add continue to check next ipc reponse.

HighCVSS 8.1Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race in Linux’s in-kernel SMB server, ksmbd, can mix up two kinds of internal messages and access unintended memory. A network attacker may be able to affect data confidentiality, integrity, or system availability, although exploitation requires winning a difficult timing condition.

Executive priority

Treat externally or broadly reachable ksmbd servers as high priority and expedite supported kernel updates. Prioritize systems handling sensitive SMB data. The absence of documented active exploitation lowers immediate crisis urgency, but it does not remove the potential for severe impact.

Technical view

Reused request handles can collide between ksmbd login requests and FSCTL_PIPE_TRANSCEIVE operations. Although ksmbd checks the IPC response type, a missing continuation permits an incorrectly typed response to be delivered, causing type confusion and unexpected memory access. CVSS 3.1 rates it 8.1: network-accessible, unauthenticated, no user interaction, but high complexity.

Likely exposure

Exposure is most likely on Linux systems actively using ksmbd and reachable by untrusted SMB clients. Systems not using the in-kernel ksmbd server are unlikely to expose this path. The supplied affected-version data is ambiguous, so confirm applicability through the Linux distributor.

Exploitation context

The supplied record does not identify public exploitation, and the CVE is not listed as KEV. The high-complexity race condition may reduce reliability, but unauthenticated network reachability and potentially severe memory effects make exposed ksmbd servers important to address.

Researcher notes

This is a CWE-362 race condition involving ID allocation and IPC response matching. Confirm remediation through commit ancestry or documented distribution backports rather than version strings alone. The supplied sources establish unexpected memory access, but do not establish reliable code execution, a public proof of concept, or exploitation in the wild.

Mitigation direction

  • Apply a vendor-supported kernel update containing the applicable upstream stable fix.
  • Check the Linux distributor’s advisory and package changelog for this CVE or a referenced fix commit.
  • If updating is delayed, consult vendor guidance for supported mitigations; none are specified in the supplied sources.

Validation and detection

  • Inventory Linux hosts and determine whether the in-kernel ksmbd SMB server is enabled or loaded.
  • Record kernel packages and versions; compare them with distributor guidance for CVE-2025-21947.
  • Confirm the installed kernel includes the relevant stable fix or a documented vendor backport.
  • After updating, verify the corrected kernel is running and repeat ksmbd exposure checks.
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

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cwe · low confidence lookup

CWE-362: Exact CWE lookup

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cve · low confidence lookup

CVE-2025-21947 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.1 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/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
7Source links

SSVC decision data

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

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
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Linux
4.7CVSS 3.1MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H13.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

8.1High
CVSS 3.1 vector shape for CVE-2025-21947Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/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, 0626e6641f6b467447c81dd7678a69c66f7746cfunaffected
LinuxLinux5.15, 0, 6.1.131, 6.6.83, 6.12.19, 6.13.7, 6.14affected
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.

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