CVE-2021-0956Network attack vector

Remote privilege escalation via unchecked technology count

Published Dec 15, 2021 · Updated Aug 3, 2024

Out-of-bounds write in Android 11 and 12 NFC tag activation allows remote attackers to gain System execution privileges. NfcTag::discoverTechnologies increments mNumTechList after erroneous activation handling without first enforcing the technology-list bound. A crafted NFC interaction reaches the flaw without authentication or user interaction and can corrupt memory in the privileged NFC process.

CVSS severity9.8
Critical
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Android 11 and 12 NFC tag activation allows remote attackers to gain System execution privileges. NfcTag::discoverTechnologies increments mNumTechList after erroneous activation handling without first enforcing the technology-list bound. A crafted NFC interaction reaches the flaw without authentication or user interaction and can corrupt memory in the privileged NFC process.

The record

CVE
CVE-2021-0956
Published
Dec 15, 2021
Updated
Aug 3, 2024
Vendor
Google Cloud
Product
Android
Classifications
CWE-787, T1404
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Android-11 Android-12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Google Cloud · Androidversion=Android-11 Android-12

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
10.0NIST NVDAV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1404Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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