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CVE Record

CVE-2021-47596: net: hns3: fix use-after-free bug in hclgevf_send_mbx_msg

In the Linux kernel, the following vulnerability has been resolved: net: hns3: fix use-after-free bug in hclgevf_send_mbx_msg Currently, the hns3_remove function firstly uninstall client instance, and then uninstall acceletion engine device. The netdevice is freed in client instance uninstall process, but acceletion engine device uninstall process still use it to trace runtime information. This causes a use after free problem. So fixes it by check the instance register state to avoid use after free.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory-safety bug in the hns3 network driver. During device removal, one component can free a network device while another removal path still uses it. The public record does not provide severity, CVSS, or confirmed exploitation evidence, so urgency depends on whether affected kernels and hns3 hardware or driver paths are present.

Executive priority

Treat this as a targeted kernel maintenance item, not a broad emergency from the available evidence. Raise priority where hns3-based networking is used, because kernel use-after-free defects can affect platform stability and may become more serious if exploit details emerge.

Technical view

CVE-2021-47596 is a use-after-free in hclgevf_send_mbx_msg related to hns3_remove ordering. The client instance uninstall frees the netdevice, while accelerator engine device uninstall can still reference it for runtime tracing. The kernel fix checks instance registration state before use to avoid dereferencing freed memory.

Likely exposure

Likely exposure is limited to Linux systems running affected kernel versions or commits with the hns3 driver path in use. The bundle lists Linux 5.8, 5.10.88, 5.15.11, and 5.16 as affected, but distribution backports require vendor-specific confirmation.

Exploitation context

The source bundle marks KEV as false and provides no cited evidence of active exploitation or public exploit use. The bug is kernel memory corruption, but the available record does not describe attacker prerequisites, reachability, privilege impact, or exploit reliability.

Researcher notes

The record lacks CVSS, CWE, exploitability analysis, and detailed attack preconditions. Analysis should focus on commit lineage, distro backports, hns3 driver deployment, and whether the vulnerable removal path can be triggered by unprivileged, local, or device-adjacent actors.

Mitigation direction

  • Apply vendor or distribution kernel updates that include the referenced stable fixes.
  • Prioritize systems using the hns3 driver or affected network hardware paths.
  • Check Linux distribution advisories for backported fixes and package-specific status.
  • If no update is available, follow vendor guidance for risk reduction.

Validation and detection

  • Inventory kernel versions against the affected versions listed in the CVE bundle.
  • Check whether the hns3 driver is present, loaded, or required on production hosts.
  • Confirm installed kernel packages include one of the referenced stable fixes or distro backports.
  • Review reboot status so patched kernels are actually running.
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-2021-47596 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

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

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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxd8355240cf8fb8b9e002b5c8458578435cea85c2, d8355240cf8fb8b9e002b5c8458578435cea85c2, d8355240cf8fb8b9e002b5c8458578435cea85c2unaffected
LinuxLinux5.8, 0, 5.10.88, 5.15.11, 5.16affected
Weakness

CWE details

No CWE listed

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