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CVE Record

CVE-2025-38562: ksmbd: fix null pointer dereference error in generate_encryptionkey

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference error in generate_encryptionkey If client send two session setups with krb5 authenticate to ksmbd, null pointer dereference error in generate_encryptionkey could happen. sess->Preauth_HashValue is set to NULL if session is valid. So this patch skip generate encryption key if session is valid.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel ksmbd flaw can crash or disrupt SMB service handling when a client sends repeated Kerberos session setup requests. The source bundle does not provide CVSS, confirmed exploit activity, or full impact details, so urgency depends on whether ksmbd with Kerberos authentication is exposed in your environment.

Executive priority

Prioritize review where Linux file-sharing servers use ksmbd and are reachable by broad internal or external clients. With no CVSS or confirmed exploitation in the bundle, this is not automatically critical, but exposed SMB services deserve prompt patch validation.

Technical view

The issue is a null pointer dereference in ksmbd generate_encryptionkey. After a valid session, sess->Preauth_HashValue may be NULL; a second Kerberos session setup can still reach encryption key generation. The stable fix skips key generation when the session is already valid.

Likely exposure

Likely limited to Linux systems using the in-kernel ksmbd SMB server, especially where Kerberos authentication is enabled. Exposure is higher if SMB service is reachable by untrusted clients. The source bundle does not establish exposure for Samba user-space smbd.

Exploitation context

The bundle describes a trigger involving two Kerberos-authenticated session setup requests. KEV status is false, and no provided source states active exploitation. Treat public exploitability as unconfirmed from this evidence.

Researcher notes

Evidence supports a kernel null dereference in ksmbd session setup logic, apparently reachable through repeated Kerberos authentication. Impact is most defensibly described as availability risk unless vendor advisories provide stronger claims. Affected version data in the bundle is incomplete and should be verified against distribution kernels.

Mitigation direction

  • Apply vendor kernel updates containing the referenced stable ksmbd fixes.
  • Check Debian LTS and distribution advisories for packaged kernel guidance.
  • Disable ksmbd if it is not required for business operations.
  • Restrict SMB access to trusted networks and authenticated clients.
  • Review Kerberos-enabled ksmbd deployments before internet-facing systems.

Validation and detection

  • Inventory Linux hosts running ksmbd, not just Samba smbd.
  • Confirm kernel versions against vendor advisories and stable fix commits.
  • Identify systems exposing SMB ports to untrusted networks.
  • Check whether ksmbd Kerberos authentication is enabled.
  • Review logs for unexpected ksmbd crashes or session setup errors.
Prepared
Confidence
medium
Sources
11

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

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CVE-2025-38562 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
10Source 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

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cfunaffected
LinuxLinux5.15, 0, 5.15.203, 6.1.148, 6.6.102, 6.12.42, 6.15.10, 6.16.1, 6.17affected
Weakness

CWE details

No CWE listed

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