dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 2 May 2022.
AndroidOperating system · Google

CVE-2021-39793

HIGH · 7.8 CVSS v3.1 Published 2022-03-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
In the wild 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 kbase_jd_user_buf_pin_pages of mali_kbase_mem.c, there is a possible out of bounds write due to a logic error in the code. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-210470189References: N/A

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 · high confidence

A logic error in the kbase_jd_user_buf_pin_pages function of the Mali GPU kernel driver (mali_kbase_mem.c) causes an out-of-bounds write vulnerability. This allows a local attacker to escalate privileges without any user interaction, as the flaw exists in kernel-space memory management code for user buffer pinning.

MitigationApply the vendor-provided kernel security patch for CVE-2021-39793, which corrects the logic error in the Mali GPU driver's user buffer pinning code. The fix requires updating to a patched Android kernel version from the device manufacturer.

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. Confirm Mali GPU kernel driver is loaded
    Check if the mali_kbase module is loaded by running 'lsmod | grep mali' or examining /proc/modules for 'mali_kbase'
    Affected if The mali_kbase module is not present, the device does not use a Mali GPU and is not affected by this specific vulnerability
  2. Identify the Mali GPU driver version
    Check the driver version via 'cat /sys/module/mali_kbase/version' or by examining the kernel module file info with 'modinfo mali_kbase'
    Affected if The driver version cannot be determined or the version is older than the patched variant for this CVE (Google Android patch level post-November 2021)
  3. Verify Android security patch level
    Run 'getprop ro.build.version.security_patch' to check the installed security patch level
    Affected if The security patch level is earlier than November 2021, indicating the vendor fix has not been applied
  4. Check for the vulnerable function in the driver
    Extract and examine the mali_kbase_mem.c driver file from the device kernel or vendor firmware image, then locate the kbase_jd_user_buf_pin_pages function and inspect the bounds checking logic around user buffer pinning
    Affected if The function contains the logic error where the bounds check uses incorrect comparison (e.g., compares page count to wrong limit) allowing out-of-bounds write
  5. Confirm the attack surface is reachable
    Verify that the kbase job dispatcher (JD) interface is accessible and user-space applications can trigger the kbase_jd_user_buf_pin_pages function through GPU memory operations
    Affected if The vulnerable code path is exposed through the JD user-space interface and can be triggered by local applications

The environment is affected if it runs Google Android with a Mali GPU kernel driver (mali_kbase) that has a security patch level earlier than November 2021 and contains the logic error in the kbase_jd_user_buf_pin_pages bounds checking.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided kernel security patch for CVE-2021-39793, which corrects the logic error in the Mali GPU driver's user buffer pinning code. The fix requires updating to a patched Android kernel version from the device manufacturer.

Fix this in Android Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,460
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,536.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-39793 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2021-39793 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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