CVE-2021-39725
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 gasket_free_coherent_memory_all of gasket_page_table.c, there is a possible memory corruption due to a double free. 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-151454974References: 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 confidenceA double free vulnerability exists in the gasket_free_coherent_memory_all function within the Android kernel's gasket_page_table.c driver. The function frees memory twice, causing heap corruption that can be exploited for local privilege escalation from System-level 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.
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Verify Android kernel is in useRun `uname -a` and confirm the kernel identifier contains 'Android' or check `/proc/version`Affected if The system is running a Google Android kernel
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Check if gasket driver is present in the kernelInspect `/proc/kallsyms` for symbols containing 'gasket' (e.g., `grep -i gasket /proc/kallsyms`) or check for kernel config option CONFIG_GASKET_DRIVER in `/boot/config-$(uname -r)` or `/proc/config.gz` if availableAffected if The gasket driver symbols or CONFIG_GASKET_DRIVER are present in the running kernel
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Verify the vulnerable function existsSearch for the function name in `/proc/kallsyms` using `grep -i gasket_free_coherent_memory /proc/kallsyms`Affected if The function `gasket_free_coherent_memory_all` symbol appears in the kernel symbol table, indicating the vulnerable code path is compiled in
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Confirm gasket module or built-in driver statusCheck if the gasket driver is loaded as a module via `lsmod | grep gasket` or listed as enabled in kernel config; if built-in, it is loaded at bootAffected if The gasket driver is either loaded as a module or compiled as built-in (CONFIG_GASKET_DRIVER=y)
If the system runs an Android kernel with the gasket driver present (as module or built-in), it is affected by this double-free vulnerability since all Android versions contain the flaw in the gasket driver code.
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 upstream kernel patch for A-151454974 to fix the double free in the gasket driver; this requires rebuilding and deploying an updated Android kernel image to affected devices.
- Consultation4.0 h
- Implementation8.0 h
- Testing16.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,152.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39725 — 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-2021-39725 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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- Version or environment caveats, and links to real fixes
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