CVE-2021-31795Public exploit

Kernel heap overwrite via unchecked mapping-table index

Published Apr 24, 2021 · Updated Aug 3, 2024

Out-of-bounds write in the PowerVR GPU kernel driver on Alcatel 1S phones through 2021-04-24 allows local users to overwrite kernel heap memory. The _PMRCreate path sizes a translation array by ui32NumVirtChunks, then indexes it with unchecked values copied from the user-controlled pui32MappingTable. Access to the driver ioctl from a low-privileged process is required; published testing demonstrates corruption and crashes, but its root-escalation race did not succeed.

CVSS severity7.0
High
EPSS probability0.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in the PowerVR GPU kernel driver on Alcatel 1S phones through 2021-04-24 allows local users to overwrite kernel heap memory. The _PMRCreate path sizes a translation array by ui32NumVirtChunks, then indexes it with unchecked values copied from the user-controlled pui32MappingTable. Access to the driver ioctl from a low-privileged process is required; published testing demonstrates corruption and crashes, but its root-escalation race did not succeed.

The record

CVE
CVE-2021-31795
Published
Apr 24, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.9NIST NVDAV:L/AC:M/Au:N/C:C/I:C/A:C
7.0NIST NVDCVSS:3.1/AV:L/AC:H/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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

Public exploit references

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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