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CVE Record

CVE-2025-22039: ksmbd: fix overflow in dacloffset bounds check

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix overflow in dacloffset bounds check The dacloffset field was originally typed as int and used in an unchecked addition, which could overflow and bypass the existing bounds check in both smb_check_perm_dacl() and smb_inherit_dacl(). This could result in out-of-bounds memory access and a kernel crash when dereferencing the DACL pointer. This patch converts dacloffset to unsigned int and uses check_add_overflow() to validate access to the DACL.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A flaw in Linux’s ksmbd SMB server can let a network user with low-level privileges trigger invalid kernel memory access. The documented result is a kernel crash, potentially disrupting file-sharing services or the entire host. The supplied CVSS score is 8.8, but the sources do not establish active exploitation.

Executive priority

Prioritize remediation for exposed ksmbd file servers because a low-privileged network user may cause a kernel-level outage. Treat internet-facing or broadly reachable systems as urgent. Other Linux hosts require exposure validation before escalation.

Technical view

An integer overflow in dacloffset arithmetic could bypass bounds checks in smb_check_perm_dacl() and smb_inherit_dacl(). Dereferencing the resulting out-of-bounds DACL pointer could crash the kernel. The fix changes dacloffset to unsigned int and validates the addition with check_add_overflow().

Likely exposure

Exposure requires Linux systems using ksmbd, with SMB reachable by an attacker possessing low privileges. The supplied affected-version data is not a clear release range, so kernel builds should be mapped against vendor advisories and the referenced stable fixes.

Exploitation context

The CVSS vector indicates network access, low attack complexity, low privileges, and no user interaction. The supplied bundle marks the CVE as absent from KEV and provides no evidence of active exploitation or a public exploit. Kernel compromise is not demonstrated by the description; the explicitly documented outcome is a crash.

Researcher notes

The core weakness is overflow-prone pointer-boundary arithmetic during DACL processing. The sources document out-of-bounds access and kernel crash, but do not substantiate code execution, data theft, or active exploitation. The affected-version list is ambiguous and includes commit identifiers and release labels without explicit ranges; rely on distribution-specific mapping.

Mitigation direction

  • Install a distribution-supported kernel containing the applicable referenced stable fix.
  • Reboot into the updated kernel and confirm the running version changed.
  • If updating is delayed, consult the Linux distribution for supported mitigations; the sources name no workaround.
  • Prioritize hosts where ksmbd serves SMB to untrusted or broadly accessible networks.

Validation and detection

  • Inventory systems with ksmbd enabled or actively serving SMB connections.
  • Compare each running kernel build with distribution advisories and the referenced stable commits.
  • Confirm the patched kernel is running after reboot, not merely installed.
  • Review kernel logs for ksmbd crashes or DACL-related memory faults.
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-2025-22039 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/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
0ADP providers
5Source 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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.8High
CVSS 3.1 vector shape for CVE-2025-22039Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cf, 0626e6641f6b467447c81dd7678a69c66f7746cfunaffected
LinuxLinux5.15, 0, 6.12.23, 6.13.11, 6.14.2, 6.15affected
Weakness

CWE details

No CWE listed

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