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CVE Record

CVE-2023-54250: ksmbd: avoid out of bounds access in decode_preauth_ctxt()

In the Linux kernel, the following vulnerability has been resolved: ksmbd: avoid out of bounds access in decode_preauth_ctxt() Confirm that the accessed pneg_ctxt->HashAlgorithms address sits within the SMB request boundary; deassemble_neg_contexts() only checks that the eight byte smb2_neg_context header + (client controlled) DataLength are within the packet boundary, which is insufficient. Checking for sizeof(struct smb2_preauth_neg_context) is overkill given that the type currently assumes SMB311_SALT_SIZE bytes of trailing Salt.

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 bug in ksmbd, the in-kernel SMB server. A malformed SMB negotiation request could make the kernel read outside the expected request boundary. The public record does not provide CVSS, impact details, or evidence of exploitation, so urgency depends on whether ksmbd is enabled and reachable.

Executive priority

Treat as a targeted Linux SMB exposure review, not a confirmed emergency. Prioritize assets where ksmbd is enabled and reachable, then remediate through normal kernel update channels once vendor-fixed builds are available.

Technical view

The flaw is in decode_preauth_ctxt(). The fix adds boundary validation for pneg_ctxt->HashAlgorithms because deassemble_neg_contexts() only checked the SMB2 negotiate-context header plus client-controlled DataLength, not the specific preauthentication context access. Sources describe affected Linux kernel ranges and stable kernel fixes.

Likely exposure

Exposure is most likely on Linux systems running ksmbd for SMB file sharing. Systems not using the in-kernel SMB server are less likely exposed. The provided data lists Linux as affected but does not identify distributions, appliances, or default configurations.

Exploitation context

No active exploitation is cited, and the CVE is not marked in KEV. The sources describe a client-controlled SMB request parsing boundary issue, but they do not state practical exploitability, required authentication, crash behavior, information disclosure, or code execution impact.

Researcher notes

The record is sparse: no CVSS, CWE, exploit report, or detailed impact is provided. Analysis should focus on ksmbd negotiate-context parsing, the preauth context boundary check, and whether downstream kernels backported the stable fixes.

Mitigation direction

  • Inventory Linux systems running ksmbd or in-kernel SMB server functionality.
  • Update to vendor kernel packages containing the referenced stable fixes.
  • Prioritize internet-reachable or untrusted-network SMB services first.
  • If updates are unavailable, check vendor guidance for supported interim controls.

Validation and detection

  • Confirm whether ksmbd is built, loaded, and enabled on Linux assets.
  • Compare running kernel versions against vendor advisories and fixed package versions.
  • Review exposure of SMB services to untrusted networks.
  • Track remediation against the linked stable kernel commits or distributor backports.
Prepared
Confidence
medium
Sources
6

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-2023-54250 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
0ADP providers
5Source 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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9, e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9unaffected
LinuxLinux5.15, 0, 5.15.145, 6.1.25, 6.2.12, 6.3affected
Weakness

CWE details

No CWE listed

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