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CVE Record

CVE-2023-53273: Drivers: vmbus: Check for channel allocation before looking up relids

In the Linux kernel, the following vulnerability has been resolved: Drivers: vmbus: Check for channel allocation before looking up relids relid2channel() assumes vmbus channel array to be allocated when called. However, in cases such as kdump/kexec, not all relids will be reset by the host. When the second kernel boots and if the guest receives a vmbus interrupt during vmbus driver initialization before vmbus_connect() is called, before it finishes, or if it fails, the vmbus interrupt service routine is called which in turn calls relid2channel() and can cause a null pointer dereference. Print a warning and error out in relid2channel() for a channel id that's invalid in the second kernel.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2023-53273 is a Linux kernel availability flaw in the Hyper-V VMBus driver. Under kdump/kexec-style reboot conditions, an interrupt can arrive before channel data is allocated, causing a kernel null pointer dereference. The likely business impact is a crash or outage of affected Linux guests, not data theft.

Executive priority

Schedule remediation through normal kernel patching, with higher priority for critical Hyper-V-hosted Linux workloads. This is not evidenced as actively exploited, but it can cause service disruption where affected conditions exist.

Technical view

The VMBus relid2channel() path assumed the channel array existed. During second-kernel boot after kdump/kexec, stale host relids and early VMBus interrupts can reach the ISR before vmbus_connect() completes or if it fails, triggering CWE-476 null pointer dereference. The fix adds validation and errors out for invalid channel IDs.

Likely exposure

Exposure is most relevant to Linux systems running as Hyper-V guests with the VMBus driver, especially environments using kdump or kexec. The CVE record lists Linux kernel versions as affected and references stable kernel commits. Distribution backports may change exposure, so package-level validation is required.

Exploitation context

The CVSS vector is local, low complexity, low privileges, no user interaction, with high availability impact. The provided sources do not indicate remote exploitation, public weaponization, or CISA KEV listing. Treat this as a stability and denial-of-service risk for affected virtualized Linux workloads.

Researcher notes

The issue is narrowly tied to VMBus initialization ordering and relid handling in second-kernel scenarios. Evidence supports availability impact only. The public bundle provides upstream stable commit references but not distribution-specific advisories, exploit reports, or operational mitigations beyond applying fixed kernels.

Mitigation direction

  • Update affected Linux kernels using your distribution or vendor security guidance.
  • Prioritize Hyper-V guest systems that use kdump or kexec workflows.
  • Confirm vendor kernels include the referenced upstream stable fixes.
  • If immediate updating is not possible, review vendor guidance for supported workarounds.

Validation and detection

  • Inventory Linux kernels running on Hyper-V guests.
  • Check whether installed kernel packages include fixes for CVE-2023-53273.
  • Review crash logs for VMBus-related null pointer dereferences during kdump or kexec boot paths.
  • Validate remediation in staging before production rollout.
Prepared
Confidence
high
Sources
7

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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cwe · low confidence lookup

CWE-476: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

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cve · low confidence lookup

CVE-2023-53273 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
6Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

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
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2023-53273Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux8b6a877c060ed6b86878fe66c7c6493a6054cf23, 8b6a877c060ed6b86878fe66c7c6493a6054cf23, 8b6a877c060ed6b86878fe66c7c6493a6054cf23, 8b6a877c060ed6b86878fe66c7c6493a6054cf23, 8b6a877c060ed6b86878fe66c7c6493a6054cf23unaffected
LinuxLinux5.8, 0, 5.10.178, 5.15.107, 6.1.24, 6.2.11, 6.3affected
Weakness

CWE details

CWE-476

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

CWE-476 · source CWE mapping

NULL Pointer Dereference

NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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