CVE-2021-47311

Local privilege escalation via EMAC teardown use-after-free

Published May 21, 2024 · Updated May 11, 2026

Use-after-free in the Qualcomm EMAC driver in Linux allows local users to corrupt kernel memory during network-device removal. In emac_remove, free_netdev() releases the network device and its private adpt data before later cleanup code dereferences adpt, leaving a stale pointer in the teardown path. Reachability requires the affected Qualcomm EMAC driver and execution of its device-removal path; the resulting corruption enables a kernel crash or privilege escalation.

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 Qualcomm EMAC driver in Linux allows local users to corrupt kernel memory during network-device removal. In emac_remove, free_netdev() releases the network device and its private adpt data before later cleanup code dereferences adpt, leaving a stale pointer in the teardown path. Reachability requires the affected Qualcomm EMAC driver and execution of its device-removal path; the resulting corruption enables a kernel crash or privilege escalation.

The record

CVE
CVE-2021-47311
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=4.9
  2. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <11e9d163d631198bb3eb41a677a61b499516c0f7
  3. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <2b70ca92847c619d6264c7372ef74fcbfd1e048c
  4. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <4d04a42b926e682140776e54188f4a44f1f01a81
  5. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <8a225a6e07a57a1538d53637cb3d82bd3e477839
  6. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <ad297cd2db8953e2202970e9504cab247b6c7cb4
  7. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <b1e091331920f8fbfc747dcbd16263fcd71abb2d
  8. Affected versionversion=54e19bc74f3380d414681762ceed9f7245bc6a6e <b560521eca03d0a2db6093a5a632cbdd0a0cf833

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.9; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <11e9d163d631198bb3eb41a677a61b499516c0f7; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <2b70ca92847c619d6264c7372ef74fcbfd1e048c; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <4d04a42b926e682140776e54188f4a44f1f01a81; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <8a225a6e07a57a1538d53637cb3d82bd3e477839; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <ad297cd2db8953e2202970e9504cab247b6c7cb4; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <b1e091331920f8fbfc747dcbd16263fcd71abb2d; version=54e19bc74f3380d414681762ceed9f7245bc6a6e <b560521eca03d0a2db6093a5a632cbdd0a0cf833

Published CVSS scores

7.8NIST National Vulnerability DatabaseCVSS: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.

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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
T1068Exploitation for Privilege Escalation

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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