CVE-2021-47064Network attack vector

DMA resource exhaustion via uninitialized skip_unmap flag

Published Feb 29, 2024 · Updated May 11, 2026

DMA resource leak in Linux 5.10 through 5.12 allows attackers to consume mappings during mt76 MCU command transmission. An uninitialized stack buffer leaves skip_unmap nonzero, causing completion handling to skip DMA unmapping for MCU command frames. The affected path requires the mt76 MediaTek wireless driver; the public record does not identify how remote traffic controls the stack-derived flag.

CVSS severity5.3
Medium
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

DMA resource leak in Linux 5.10 through 5.12 allows attackers to consume mappings during mt76 MCU command transmission. An uninitialized stack buffer leaves skip_unmap nonzero, causing completion handling to skip DMA unmapping for MCU command frames. The affected path requires the mt76 MediaTek wireless driver; the public record does not identify how remote traffic controls the stack-derived flag.

The record

CVE
CVE-2021-47064
Published
Feb 29, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 29, 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=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <91b9548d413fda488ea853cd1b9f59b572db3a0c
  2. Affected versionversion=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <9b68ce2856dadc0e1cb6fd21fbeb850da49efd08
  3. Affected versionversion=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <9fa26701cd1fc4d932d431971efc5746325bdfce
  4. Affected versionversion=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <b4403cee6400c5f679e9c4a82b91d61aa961eccf
  5. Affected versionversion=5.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <91b9548d413fda488ea853cd1b9f59b572db3a0c; version=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <9b68ce2856dadc0e1cb6fd21fbeb850da49efd08; version=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <9fa26701cd1fc4d932d431971efc5746325bdfce; version=27d5c528a7ca08dcd44877fdd9fc08b76630bf77 <b4403cee6400c5f679e9c4a82b91d61aa961eccf; version=5.10

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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