CVE-2021-0920

Exp

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

Published: 2021-12-15 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-0920 is rated Active Exploitation (70/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.81%). CISA KEV confirms active exploitation (added 2022-05-23) affecting Android / Kernel. a weakness (CWE-362) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

CISA KEV Record for CVE-2021-0920

Name: Android Kernel Race Condition Vulnerability · CISA KEV detail

Exploit added: 2022-05-23

Action due: 2022-06-13

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2021-0920

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.94% 0.81% -0.13%
2 2025-11-21 0.18% 0.94% +0.77%
3 2025-11-18 — 0.18% —

Full EPSS history (15 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-0920

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.4 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.5 5.9 [email protected]
6.4 3.1 MEDIUM
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.5 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0
6.9 2.0 MEDIUM
AV:L/AC:M/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.4 10.0 [email protected]

Weakness enumeration for CVE-2021-0920

OS Trackers for CVE-2021-0920

vendor priority summary link
debian not yet assigned CVE-2021-0920 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-0920
redhat high — https://access.redhat.com/security/cve/CVE-2021-0920
suse high — https://www.suse.com/security/cve/CVE-2021-0920/
ubuntu high CVE-2021-0920 high priority: Ubuntu including 167 source packages (linux, linux-allwinner, …), 2101 status rows across 15 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1627, released 228, not-affected 208, ignored 37, needed 1. https://ubuntu.com/security/CVE-2021-0920

Affected software / configurations for CVE-2021-0920

Vendor Product Version Raw CPE
linux linux_kernel <= 5.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 5.14 cpe:2.3:o:linux:linux_kernel:5.14:rc1:*:*:*:*:*:*
linux linux_kernel 5.14 cpe:2.3:o:linux:linux_kernel:5.14:rc2:*:*:*:*:*:*
linux linux_kernel 5.14 cpe:2.3:o:linux:linux_kernel:5.14:rc3:*:*:*:*:*:*
google android — cpe:2.3:o:google:android:-:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2021-0920

cvelogic Threat Intelligence