dbcve.org
AndroidOperating system · Google

CVE-2021-39661

HIGH · 7.8 CVSS v3.1 Published 2022-11-08
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In _PMRLogicalOffsetToPhysicalOffset of the PowerVR kernel driver, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android SoCAndroid ID: A-246824784

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Out of bounds write vulnerability in the PowerVR kernel driver's _PMRLogicalOffsetToPhysicalOffset function due to missing bounds check. This allows a local attacker to write beyond allocated memory boundaries in kernel space, leading to local privilege escalation without requiring additional execution privileges or user interaction.

MitigationApply Android security patch levels that include the fix for this PowerVR kernel driver vulnerability. Contact the SoC manufacturer for driver updates if running on an affected platform.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AndroidOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify PowerVR GPU hardware
    Check /proc/cpuinfo for 'Imagination' or 'PowerVR' entries, or check /sys/class/misc/mali0/device/name for 'PowerVR' or 'Imagination' string. Alternatively, use 'lshw' or check dmesg for PowerVR driver loading.
    Affected if The device contains a PowerVR GPU (Imagination Technologies) and loads the vulnerable kernel driver module.
  2. Verify Android security patch level
    Go to Settings > About Phone > Android version (or Security patch level on newer Android). Or run 'getprop ro.build.version.security_patch' via ADB to retrieve the patch date.
    Affected if The security patch level is earlier than the date when this vulnerability was fixed (typically December 2021 or later for affected devices).
  3. Confirm vulnerable driver module presence
    Check if the PowerVR kernel module is loaded: run 'lsmod' or check /proc/modules for entries like 'pvrsrvkm', 'imgpvrsrv', or similar PowerVR driver modules. Also check /sys/module/ for PowerVR module directories.
    Affected if The PowerVR kernel driver module (pvrsrvkm or similar) is loaded on the device.
  4. Check kernel logs for driver initialization
    Run 'dmesg | grep -i powervr' or 'dmesg | grep -i pvrsrv' to see if the PowerVR driver initialized at boot. This confirms the vulnerable code path is active.
    Affected if PowerVR driver initialization messages appear in kernel logs, indicating the vulnerable driver is active.

A device is affected if it has a PowerVR GPU and is running an Android version with a security patch level prior to the fix being applied.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply Android security patch levels that include the fix for this PowerVR kernel driver vulnerability. Contact the SoC manufacturer for driver updates if running on an affected platform.

Recommended fix High confidence

Android Security Patch Level December 2021 or later (2021-12-01)

  1. 1. Check the current Android Security Patch Level on the device (Settings > About Phone > Security Patch Level)
  2. 2. Verify the device manufacturer has released a security update containing the fix for CVE-2021-39661
  3. 3. Apply the latest available Android security update from the device manufacturer
  4. 4. For devices no longer receiving official updates, consider replacing with a device that still receives monthly security patches
  5. 5. Alternatively, if the device supports it, install a custom ROM that includes the latest kernel security patches
Caveat Security updates may not be available for older or end-of-life devices; some devices may not receive monthly updates from manufacturers

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation10.0 h
  • Implementation8.0 h
  • Testing20.0 h
  • Review / QA6.0 h
44.0 hours of engineering $7,520
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39661 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data