CVE-2021-0929

Local privilege escalation via premature DMA-BUF unmapping

Published Dec 15, 2021 · Updated Aug 3, 2024

Use-after-free in Android kernel ION allows local users to escalate privileges through a crafted DMA-BUF synchronization request. The ion_dma_buf_end_cpu_access path lets userspace DMA_BUF_SYNC_END decrement the shared kmap counter and unmap a buffer still mapped by a device driver. A local low-privileged process needs no user interaction and can use the resulting stale mapping to corrupt kernel memory and gain elevated privileges.

CVSS severity7.8
High
EPSS probability0.16%
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 Android kernel ION allows local users to escalate privileges through a crafted DMA-BUF synchronization request. The ion_dma_buf_end_cpu_access path lets userspace DMA_BUF_SYNC_END decrement the shared kmap counter and unmap a buffer still mapped by a device driver. A local low-privileged process needs no user interaction and can use the resulting stale mapping to corrupt kernel memory and gain elevated privileges.

The record

CVE
CVE-2021-0929
Published
Dec 15, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-416, T1404
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=Android kernel

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Google Cloud · Androidversion=Android kernel

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

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
T1404Exploitation 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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