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CVE Record

CVE-2026-43106: cachefiles: fix incorrect dentry refcount in cachefiles_cull()

In the Linux kernel, the following vulnerability has been resolved: cachefiles: fix incorrect dentry refcount in cachefiles_cull() The patch mentioned below changed cachefiles_bury_object() to expect 2 references to the 'rep' dentry. Three of the callers were changed to use start_removing_dentry() which takes an extra reference so in those cases the call gets the expected references. However there is another call to cachefiles_bury_object() in cachefiles_cull() which did not need to be changed to use start_removing_dentry() and so was not properly considered. It still passed the dentry with just one reference so the net result is that a reference is lost. To meet the expectations of cachefiles_bury_object(), cachefiles_cull() must take an extra reference before the call. It will be dropped by cachefiles_bury_object().

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel CacheFiles cleanup path mishandles an internal object reference, potentially causing serious local security impact. The supplied CVSS score is 7.8, reflecting possible confidentiality, integrity, and availability loss. Exposure depends on the affected kernel code and use of CacheFiles.

Executive priority

Treat as a high-priority kernel maintenance issue on systems using CacheFiles. Accelerate inventory and vendor-supported patching, but do not characterize it as an active emergency without exploitation evidence. Resolve ambiguous version boundaries through distribution-specific advisories.

Technical view

cachefiles_cull() passed a dentry to cachefiles_bury_object() with one reference although the callee expected two. The resulting lost reference creates unsafe kernel object-lifetime handling. The fix takes an additional reference before the call, which cachefiles_bury_object() subsequently releases.

Likely exposure

Prioritize Linux systems matching the bundle’s affected version data, particularly those using CacheFiles. The supplied range information names 6.19, 6.19.14, and 7.0 but is not sufficiently structured to establish precise boundaries. Confirm exposure against distribution or kernel vendor guidance and the linked fixes.

Exploitation context

The CVSS vector describes a local, low-complexity attack requiring low privileges and no user interaction. The source bundle marks this CVE as absent from KEV and provides no evidence of active exploitation or a public exploit. Practical reachability conditions beyond the CacheFiles culling path are not documented.

Researcher notes

The defect follows an earlier contract change requiring two references to the rep dentry. Three callers gained an extra reference through start_removing_dentry(), but cachefiles_cull() did not. The corrective commits add the missing reference. No CWE classification, crash signature, proof of concept, or detailed exploitation prerequisites are supplied.

Mitigation direction

  • Identify systems running affected Linux kernel builds and determine whether CacheFiles is used.
  • Apply a vendor-supported kernel update containing the referenced fix or its verified backport.
  • If updates are delayed, consult vendor guidance for supported temporary mitigations.
  • Consider limiting CacheFiles use only after assessing availability and operational consequences.

Validation and detection

  • Record each system’s running kernel build, package release, and distribution.
  • Compare builds with vendor advisories and the source bundle’s affected-version data.
  • Verify the installed kernel contains either referenced fix or an equivalent vendor backport.
  • Confirm updated systems boot successfully and exercise relevant CacheFiles workloads through regression testing.
Prepared
Confidence
medium
Sources
4

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-2026-43106 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/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
3Source 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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-43106Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/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
LinuxLinux7bb1eb45e43c4730cbc5a48b9e9295049fccdacb, 7bb1eb45e43c4730cbc5a48b9e9295049fccdacbunaffected
LinuxLinux6.19, 0, 6.19.14, 7.0affected
Weakness

CWE details

No CWE listed

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