CVE-2021-47596

Local kernel use-after-free via stale netdevice trace

Published Jun 19, 2024 · Updated May 11, 2026

Use-after-free in the HNS3 VF driver in Linux 5.8 through 5.10.87 and 5.11 through 5.15.10 allows local users to access freed kernel memory. The hns3_remove path frees the netdevice while uninstalling the client, then acceleration-engine teardown passes the stale pointer to hclgevf_send_mbx_msg for runtime tracing. Reachability requires teardown of an affected HNS3 virtual-function device; published sources do not describe a demonstrated end effect.

CVSS severity7.8
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the HNS3 VF driver in Linux 5.8 through 5.10.87 and 5.11 through 5.15.10 allows local users to access freed kernel memory. The hns3_remove path frees the netdevice while uninstalling the client, then acceleration-engine teardown passes the stale pointer to hclgevf_send_mbx_msg for runtime tracing. Reachability requires teardown of an affected HNS3 virtual-function device; published sources do not describe a demonstrated end effect.

The record

CVE
CVE-2021-47596
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.8
  2. Affected versionversion=d8355240cf8fb8b9e002b5c8458578435cea85c2 <12512bc8f25b8ba9795dfbae0e9ca57ff13fd542
  3. Affected versionversion=d8355240cf8fb8b9e002b5c8458578435cea85c2 <27cbf64a766e86f068ce6214f04c00ceb4db1af4
  4. Affected versionversion=d8355240cf8fb8b9e002b5c8458578435cea85c2 <4f4a353f6fe033807cd026a5de81c67469ff19b0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.8; version=d8355240cf8fb8b9e002b5c8458578435cea85c2 <12512bc8f25b8ba9795dfbae0e9ca57ff13fd542; version=d8355240cf8fb8b9e002b5c8458578435cea85c2 <27cbf64a766e86f068ce6214f04c00ceb4db1af4; version=d8355240cf8fb8b9e002b5c8458578435cea85c2 <4f4a353f6fe033807cd026a5de81c67469ff19b0

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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