CVE-2021-39683
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 copy_from_mbox of sss_ice_util.c, there is a possible out of bounds write due to a missing bounds check. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-202003354References: 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 confidenceAn out-of-bounds write vulnerability exists in the copy_from_mbox function within sss_ice_util.c in the Android kernel. The flaw stems from a missing bounds check that allows writing beyond allocated buffer boundaries. This enables a local attacker with System-level privileges to escalate to higher privileges.
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.
-
Check Android Security Patch LevelGo to Settings > About Phone > Security patch level. Alternatively, run 'getprop ro.build.version.security_patch' in adb shell.Affected if The Security Patch Level is earlier than January 2022, as this vulnerability was addressed in the January 2022 Android Security Bulletin.
-
Verify Kernel VersionRun 'uname -r' in adb shell or check /proc/version. Compare the kernel version against the version that includes the fix for this CVE.Affected if The kernel version is older than the version that contains the bounds check fix in sss_ice_util.c.
-
Check for Vulnerable Module PresenceSearch for the sss_ice module by running 'ls -la /system/lib/modules/' or 'find /system -name "*sss_ice*"' in adb shell.Affected if The sss_ice module exists and the kernel lacks the CVE-2021-39683 fix.
-
Confirm System Privilege AccessVerify the attacker would need System-level privileges (run 'whoami' and 'id' in adb shell to confirm current privilege level).Affected if The device allows local processes with System-level privileges to execute, which is required to exploit this vulnerability.
A device is affected if it runs Android with a Security Patch Level before January 2022 and contains the vulnerable copy_from_mbox function in the sss_ice_util.c kernel component.
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 security patch level that addresses CVE-2021-39683. Since this is a kernel vulnerability, the fix requires updating the Android kernel with the vendor-provided patch that adds proper bounds validation in the copy_from_mbox function.
- Consultation4.0 h
- Implementation2.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39683 — 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-2021-39683 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
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.
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.
- 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