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CVE Record

CVE-2026-43274: mailbox: mchp-ipc-sbi: fix out-of-bounds access in mchp_ipc_get_cluster_aggr_irq()

In the Linux kernel, the following vulnerability has been resolved: mailbox: mchp-ipc-sbi: fix out-of-bounds access in mchp_ipc_get_cluster_aggr_irq() The cluster_cfg array is dynamically allocated to hold per-CPU configuration structures, with its size based on the number of online CPUs. Previously, this array was indexed using hartid, which may be non-contiguous or exceed the bounds of the array, leading to out-of-bounds access. Switch to using cpuid as the index, as it is guaranteed to be within the valid range provided by for_each_online_cpu().

HighCVSS 8.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel mailbox driver can read or write beyond an allocated per-CPU array when hardware CPU identifiers are non-contiguous or unexpectedly large. Affected systems could crash or suffer memory corruption. The supplied CVSS rating indicates possible confidentiality, integrity, and availability impact, but the vulnerability requires local access and the relevant driver path.

Executive priority

Treat as a high-priority platform patch for systems using the affected driver, especially sensitive or availability-critical devices. Broad emergency action across every Linux host is not supported by the supplied evidence. Establish hardware and driver exposure first, then patch confirmed systems promptly through supported vendor channels.

Technical view

The mchp-ipc-sbi driver allocated cluster_cfg according to the number of online CPUs but indexed it with hartid. Because hart IDs need not be contiguous or bounded by that count, this could cause out-of-bounds access. The kernel fix indexes by cpuid, which for_each_online_cpu() guarantees is within the allocated range.

Likely exposure

Exposure is most likely limited to systems running an affected Linux kernel and executing the mchp-ipc-sbi mailbox driver path. The bundle reports affected versions including 6.14, 6.18.16, 6.19.6, and 7.0, but its version-range semantics are incomplete; verify distribution backports and exact kernel provenance.

Exploitation context

The CVSS vector describes a local, low-complexity issue requiring no privileges or user interaction, with potentially high impact. However, the bundle marks KEV false and provides no evidence of active exploitation, a public exploit, or demonstrated practical exploitation. Trigger prerequisites beyond reaching the affected driver are not documented.

Researcher notes

The core defect is an index-domain mismatch: allocation follows online-CPU count, while access previously used hartid. The supplied record does not identify CWE classification, affected configuration prerequisites, reproducer details, or definitive version ranges. Researchers should distinguish upstream commit presence from distribution package status and avoid inferring exploitability solely from CVSS impact metrics.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable upstream stable fix.
  • Check distribution advisories for backported fixes and corrected package versions.
  • Prioritize systems that load or exercise the mchp-ipc-sbi mailbox driver.
  • If immediate updating is impossible, consult vendor guidance for supported exposure-reduction measures.

Validation and detection

  • Inventory running kernel versions and identify systems using the mchp-ipc-sbi driver.
  • Compare kernel source or package changelogs against the three referenced fix commits.
  • Confirm vendor advisories identify the installed package as fixed or unaffected.
  • After updating, verify the intended fixed kernel is running across all affected systems.
Prepared
Confidence
medium
Sources
5

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-2026-43274 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.4 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/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
0ADP providers
4Source 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
8.4CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.55.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

8.4High
CVSS 3.1 vector shape for CVE-2026-43274Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe4b1d67e71419c4af581890ecea84b04920d4116, e4b1d67e71419c4af581890ecea84b04920d4116, e4b1d67e71419c4af581890ecea84b04920d4116unaffected
LinuxLinux6.14, 0, 6.18.16, 6.19.6, 7.0affected
Weakness

CWE details

No CWE listed

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