What is CVE-2021-0920?

CVE-2021-0920 is a medium-severity vulnerability in Google Android, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.4/10. Published 2021-12-15.

How severe is CVE-2021-0920?

Medium severity. CVSS v3 base score is 6.4 out of 10.

Is CVE-2021-0920 known to be exploited?

Yes. CVE-2021-0920 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-05-23), indicating it is being actively exploited. 18 public proof-of-concept repositories are indexed.

Use After Free in Google Android

CVE-2021-0920

In unix_scm_to_skb of af_unix.c, there is a possible use after free bug 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-196926917References: Upstream kernel

Vulnerability class: Race Condition

Published 2021-12-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (58.0th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 58.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.009 · newest: 0.009 · change: +0.000

Affected products

Google Android
Linux Kernel — versions 5.14
Debian Linux — versions 9.0
Android — versions Android kernel

Weakness classification (CWE)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-05-23. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-06-13.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

source.android.com/security/bulletin/2021-11-01 (Vendor Advisory)
lists.debian.org/debian-lts-announce/2021/12/msg00012.html (mailing-list, Mailing List, Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (Third Party Advisory, US Government Resource)

Frequently asked questions

What is CVE-2021-0920?: CVE-2021-0920 is a medium-severity vulnerability in Google Android, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.4/10. Published 2021-12-15.
How severe is CVE-2021-0920?: Medium severity. CVSS v3 base score is 6.4 out of 10.
Is CVE-2021-0920 known to be exploited?: Yes. CVE-2021-0920 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-05-23), indicating it is being actively exploited. 18 public proof-of-concept repositories are indexed.