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CVE Record

CVE-2021-47070: uio_hv_generic: Fix another memory leak in error handling paths

In the Linux kernel, the following vulnerability has been resolved: uio_hv_generic: Fix another memory leak in error handling paths Memory allocated by 'vmbus_alloc_ring()' at the beginning of the probe function is never freed in the error handling path. Add the missing 'vmbus_free_ring()' call. Note that it is already freed in the .remove function.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue is a memory leak in an error path of the uio_hv_generic driver. If probing the device fails, memory allocated for a VMBus ring was not released. The CVE is rated medium and requires local low-privilege access, so it is mainly a host hardening and patch management concern.

Executive priority

Treat this as routine but necessary kernel maintenance, not an emergency. Prioritize systems with shared local users, virtualization exposure, or strict data isolation requirements. There is no source-provided evidence of active exploitation, but kernel flaws should be closed during the next controlled patch cycle.

Technical view

The vulnerable probe path allocates memory with vmbus_alloc_ring() but omits vmbus_free_ring() when later error handling runs. Upstream stable fixes add the missing free call. The source bundle lists Linux kernel versions/commits as affected and references stable kernel commits plus a Debian LTS announcement.

Likely exposure

Exposure is most likely on Linux systems running affected kernel builds where the uio_hv_generic driver and VMBus-related probing are relevant. The bundle does not prove broad internet exposure or remote reachability. Confirm exposure through kernel version, distribution advisory status, and whether this driver can load or is present.

Exploitation context

The CVSS vector indicates local access, low attack complexity, low privileges, no user interaction, unchanged scope, and high confidentiality impact. The source bundle marks CISA KEV as false and provides no cited evidence of active exploitation or public exploit availability.

Researcher notes

The key evidence is the upstream description: an error-handling leak after vmbus_alloc_ring() in uio_hv_generic probe, fixed by adding vmbus_free_ring(). The CVSS confidentiality impact appears high, but the provided description does not explain the data exposure path. Avoid overclaiming beyond local, low-privilege prerequisites.

Mitigation direction

  • Update affected Linux kernels through vendor-supported packages or stable kernel fixes.
  • Review Debian LTS or your distribution advisory for package-specific fixed versions.
  • Restrict unnecessary local user access on affected systems until updates are applied.
  • Disable or avoid loading unneeded drivers only if supported by vendor guidance.
  • Track kernel advisories for any revised impact or backport information.

Validation and detection

  • Inventory Linux kernel versions across servers, guests, and images.
  • Check whether uio_hv_generic is present, loadable, or in use.
  • Compare installed kernel packages against vendor fixed-version advisories.
  • Confirm updates include one of the referenced stable fixes or downstream backports.
  • Reboot into the updated kernel and verify the running version.
Prepared
Confidence
high
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-2021-47070 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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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:H/I:N/A:N

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
2ADP providers
5Source 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:H/I:N/A:N1.83.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2021-47070Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxcdfa835c6e5e87d145f9f632b58843de97509f2b, cdfa835c6e5e87d145f9f632b58843de97509f2b, cdfa835c6e5e87d145f9f632b58843de97509f2bunaffected
LinuxLinux4.20, 0, 5.10.241, 5.12.7, 5.13affected
Weakness

CWE details

No CWE listed

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