dbcve.org
AndroidOperating system · Google

CVE-2022-20373

MEDIUM · 6.4 CVSS v3.1 Published 2022-08-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
66/100
Remediation priority · Elevated
Zero-click

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 · unedited
In st21nfc_loc_set_polaritymode of fc/st21nfc.c, there is a possible use after free due to a race condition. 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-208269510References: 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 confidence

Race condition in Android kernel NFC driver (st21nfc) allows use-after-free in st21nfc_loc_set_polaritymode function. A local attacker with System privileges can exploit this race condition to achieve privilege escalation.

MitigationApply vendor kernel security patch for A-208269510; implement proper synchronization (mutex/spinlock) around the memory access path in the st21nfc driver to prevent the race condition.

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
AndroidOperating system
Affected:all versions

CVSS 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
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Verify st21nfc driver presence
    Check if the st21nfc kernel module is loaded: grep -i st21nfc /proc/modules (if modular) or check /sys/module/ | grep -i st21 (if built-in). On Android, also check /dev/pn544 or similar NFC device nodes and kernel config for CONFIG_NFC_ST21NFCA=y or m.
    Affected if The st21nfc driver is loaded or built into the kernel on the device
  2. Identify kernel version
    Run 'uname -r' or check /proc/version to get the exact kernel version string. Compare against known patched kernel versions for your Android security patch level.
    Affected if Kernel version predates the A-208269510 patch (no specific version number provided, but devices without May 2022 or later kernel security patches are likely vulnerable)
  3. Check Android security patch level
    Go to Settings > About Phone > Android security patch level, or run 'getprop ro.build.version.security_patch' via adb shell.
    Affected if Security patch level is earlier than May 2022 (when A-208269510 was addressed)
  4. Verify NFC hardware and driver binding
    Check if NFC is functional: run 'nfc list' (if available) or check /sys/class/nfc/ for st21nfc entries. Also inspect dmesg output for st21nfc driver initialization messages.
    Affected if NFC is enabled and the st21nfc driver is actively bound to NFC hardware

Device is affected if it contains the st21nfc NFC driver and has not received the May 2022 or later kernel security patch addressing A-208269510.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply vendor kernel security patch for A-208269510; implement proper synchronization (mutex/spinlock) around the memory access path in the st21nfc driver to prevent the race condition.

Recommended fix Moderate confidence

Latest Android security patch level (refer to Android Security Bulletin for specific release containing fix for A-208269510)

  1. Check the Android Security Bulletin for the month this vulnerability was fixed (Android ID A-208269510)
  2. Upgrade the device to the latest Android security patch level that includes the fix for this vulnerability
  3. If the device is no longer supported by the OEM, consider replacing with a device that receives regular security updates
  4. For developers: Ensure devices running affected Android versions receive the monthly security update containing the fix
Caveat Major Android version upgrades may introduce compatibility issues with existing applications; ensure testing is performed before deploying to production devices

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Android Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA6.0 h
34.0 hours of engineering $5,940
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-20373 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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