CVE-2021-0940
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 · uneditedIn TBD of TBD, there is a possible out of bounds write due to improper locking. This could lead to local escalation of privilege in the kernel with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-171315276References: 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 · moderate confidenceA kernel vulnerability in Android stemming from improper locking mechanisms that leads to an out-of-bounds memory write. This allows a local attacker with System-level execution privileges to escalate to kernel-level privileges without user interaction.
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 dataall versionsCVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/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 checksWork through these to decide whether this CVE applies to you.
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Check Android Security Patch LevelGo to Settings > About Phone > Security Patch Level, or run 'getprop ro.build.version.security_patch' via ADB shellAffected if The Security Patch Level is earlier than the February 2021 Android Security Bulletin (or earlier than when the fix was released)
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Identify the Kernel VersionRun 'uname -r' or 'cat /proc/version' in a terminal or via ADB shellAffected if The kernel version predates the fix for this locking mechanism vulnerability (compare against kernel versions that include the CVE-2021-0940 patch)
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Confirm System-Level Execution ContextVerify the device has an app or process running with System-level privileges (apps with signature|system privileges, or root/rooted context)Affected if The device has System-level or root execution context available - this is required for the attacker to exploit the vulnerability
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Check Device Support StatusCheck if the device manufacturer still provides monthly security updates via Settings > System > Software Update, or consult the manufacturer's support websiteAffected if The device is no longer receiving official Android security updates - meaning the fix cannot be applied through standard channels
A device is affected if it runs an Android version with a Security Patch Level prior to the fix release date AND has System-level execution context available on the device.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the Android kernel security patch from the relevant security bulletin. This is a kernel-level fix requiring updates through Android's monthly security update process.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-0940 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-0940 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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