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CVE Record

CVE-2025-37778: ksmbd: Fix dangling pointer in krb_authenticate

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix dangling pointer in krb_authenticate krb_authenticate frees sess->user and does not set the pointer to NULL. It calls ksmbd_krb5_authenticate to reinitialise sess->user but that function may return without doing so. If that happens then smb2_sess_setup, which calls krb_authenticate, will be accessing free'd memory when it later uses sess->user.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A Linux kernel SMB server flaw can leave a deleted user-session object referenced during Kerberos authentication. A later session-setup operation may use that invalid memory, potentially causing severe confidentiality, integrity, or availability impact. Risk is concentrated on systems running the affected ksmbd functionality, especially where SMB is network-reachable.

Executive priority

Prioritize urgent assessment of network-reachable ksmbd servers. Patch confirmed exposures promptly, while treating internet-accessible or broadly reachable SMB services as highest priority. Systems not running ksmbd are unlikely to reach the vulnerable path described.

Technical view

krb_authenticate frees sess->user without clearing the pointer. If ksmbd_krb5_authenticate returns without replacing it, smb2_sess_setup later dereferences freed memory. This is a dangling-pointer memory-safety flaw in ksmbd's Kerberos session path. The supplied CVSS 3.1 rating is 9.8, but the sources do not establish a specific realized outcome.

Likely exposure

Likely exposure is limited to Linux systems using affected ksmbd code and the relevant Kerberos authentication path. Network-reachable SMB services increase concern. The supplied affected-version data is ambiguous and should not replace distribution-specific package or kernel advisories.

Exploitation context

CISA KEV status is false in the supplied bundle, and no cited source establishes active exploitation or a public exploit. The CVSS vector describes unauthenticated, network-accessible, low-complexity risk, but that rating alone does not prove reliable exploitation.

Researcher notes

The failure condition requires ksmbd_krb5_authenticate to return without reinitializing sess->user after it was freed. The later dereference occurs in smb2_sess_setup. Sources identify stable-kernel fixes, but provide no exploit demonstration, attack telemetry, CWE assignment, or precise branch-by-branch vulnerable ranges in this bundle.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable referenced stable fix.
  • Follow Linux distribution guidance to identify the corrected package for each kernel branch.
  • Restrict network access to ksmbd services until affected systems are updated.
  • Disable unused ksmbd or Kerberos-backed SMB functionality according to vendor guidance.

Validation and detection

  • Inventory systems running ksmbd and identify their exact kernel and distribution package versions.
  • Determine whether SMB is remotely reachable and Kerberos authentication is configured.
  • Compare installed kernels with distribution advisories and the referenced stable fixes.
  • After updating, confirm systems booted into the corrected kernel.
  • Monitor kernel and SMB service logs for abnormal session failures or crashes.
Prepared
Confidence
medium
Sources
9

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.

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CVE-2025-37778 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.

1CVSS vectors
3Timeline events
1ADP providers
8Source links

CVSS vector scores

1 official score

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

Vulnerability scoring details

Base CVSS 3.1 score

9.8Critical
CVSS 3.1 vector shape for CVE-2025-37778Attack 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

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, 5.15.203, 6.1.135, 6.6.88, 6.12.25, 6.14.4, 6.15affected
Weakness

CWE details

No CWE listed

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