CVE-2021-0535
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 wpas_ctrl_msg_queue_timeout of ctrl_iface_unix.c, there is a possible memory corruption due to a use after free. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android-11Android ID: A-168314741
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 use-after-free vulnerability exists in the wpas_ctrl_msg_queue_timeout function of ctrl_iface_unix.c in Android's wpa_supplicant component. The vulnerability allows a local attacker with System-level privileges to achieve memory corruption and potentially escalate to root privileges. The issue stems from incorrect memory management where a pointer is used after the memory it references has been freed.
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= 11.0CVSS 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 version is 11.0Run 'getprop ro.build.version.release' and confirm the output is '11' or '11.0'. Only Android version 11.0 is affected by this CVE.Affected if The Android version is 11.0 exactly (Android 11, API level 30).
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Confirm wpa_supplicant is runningCheck running processes using 'ps -A | grep wpa_supplicant' or 'ps -A | grep wpa' to determine if the wpa_supplicant daemon is active on the device.Affected if wpa_supplicant is actively running as a daemon on the device.
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Verify ctrl interface UNIX socket existsCheck for the presence of the wpa_supplicant control interface socket, typically found at /data/misc/wifi/sockets/wlan0 or similar paths under /data/misc/wifi/sockets/. Use 'ls -la /data/misc/wifi/sockets/' to list available sockets.Affected if The UNIX socket for wpa_supplicant control interface exists and is accessible, indicating the ctrl_iface module is enabled.
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Check for system-level attacker accessDetermine if the device has been compromised or if untrusted applications have obtained System-level privileges (UID 1000) through 'dumpsys package <pkg>' or checking running processes with System UID.Affected if The device has an attacker with System-level (UID 1000) privileges, which is required to exploit this vulnerability.
A device is affected only if it is running Android 11.0 with wpa_supplicant actively running and its control interface UNIX socket accessible to an attacker with System-level privileges.
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 vendor patch for Android-11 (A-168314741) which corrects the memory handling in ctrl_iface_unix.c. Ensure proper null-termination of pointers after free operations and verify the fix does not introduce new race conditions in the ctrl interface message queue handling.
- Consultation3.0 h
- Implementation6.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-0535 — 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-2021-0535 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
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