Security readout for executives and security teams
Plain-English summary
This Android flaw could let a local Guest user enable NFC despite intended restrictions. It is a local privilege issue, not a remote takeover, and sources do not show active exploitation or a CVSS score. Business urgency is highest for shared, kiosk, BYOD, or managed phones where Guest accounts are allowed.
Executive priority
Treat this as a targeted mobile fleet hygiene issue, not an internet-scale emergency. Prioritize patch verification for shared or guest-accessible Android devices, especially where NFC could affect payments, access badges, or data-transfer controls.
Technical view
CVE-2021-39807 is a missing permission check in handleNfcStateChanged in SecureNfcEnabler.java. A Guest account can enable NFC without additional execution privileges or user interaction. Affected versions are Android 10, 11, 12, and 12L. Android ID is A-209446496. No CWE or CVSS is supplied in the source bundle.
Likely exposure
Exposure is limited to Android 10 through 12L devices where Guest accounts exist and NFC policy matters. Fleet risk depends on OEM patch status, Android security patch level, and whether shared-device or guest-mode workflows are enabled.
Exploitation context
The source describes local escalation of privilege from the Guest account with no user interaction needed. It does not state remote exploitability, public exploit availability, or active exploitation. The CVE is not listed as KEV in the supplied bundle.
Researcher notes
Evidence is sparse: the bundle gives the vulnerable component, permission-check weakness, affected Android versions, Android bug ID, and bulletin reference. It does not provide CVSS, CWE, detailed patch mechanics, exploit details, or confirmation of exploitation in the wild.
Mitigation direction
- Review the Android April 2022 security bulletin for vendor guidance.
- Apply relevant Android security updates from OEM or carrier channels.
- Prioritize shared, kiosk, and managed devices using Guest accounts.
- Confirm whether NFC restrictions remain enforceable after patching.
- Track OEM advisories for devices that no longer receive updates.
Validation and detection
- Inventory Android 10, 11, 12, and 12L devices.
- Check each device's Android security patch level and OEM update status.
- Identify devices where Guest account access is enabled.
- Confirm NFC policy behavior using approved administrative validation procedures.
- Document exceptions for unsupported or unpatchable devices.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-39807 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://source.android.com/security/bulletin/2022-04-01CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.