⚠ Actively exploited
Added to CISA KEV on 2022-05-23. Federal agencies required to patch by 2022-06-13. Required action: Apply updates per vendor instructions..

CVE-2021-0920 — Race Condition in Kernel

CWE-362 — Race ConditionCWE-416 — Use After Free21 documents13 sources
Severity
6.4MEDIUMNVD
OSV5.3
EPSS
0.9%
top 24.21%
CISA KEV
KEV
Added 2022-05-23
Due 2022-06-13
Exploit
Exploited in wild
Active exploitation observed
Affected products
5
Linux KernelDebian LinuxDebian Linux+2 more
Timeline
PublishedDec 15
KEV addedMay 23
KEV dueJun 13
Latest updateAug 27
CISA Required Action: Apply updates per vendor instructions.

Description

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

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:HExploitability: 0.5 | Impact: 5.9

Affected Packages6 packages

▶Debianlinux/linux_kernel< 5.10.70-1+3
▶Ubuntulinux/linux_kernel< 3.13.0-207.258+1
▶NVDlinux/linux_kernel5.13+1
▶debiandebian/linux< linux 5.14.6-1 (bookworm)

Also affects: Debian Linux 9.0

🔴Vulnerability Details

10
OSV
linux vulnerabilities↗2025-08-27
▶
Project0
The quantum state of Linux kernel garbage collection CVE-2021-0920 (Part I) - Project Zero↗2022-08-01
▶
OSV
linux, linux-aws, linux-kvm, linux-lts-xenial vulnerabilities↗2022-04-01
▶
Project0
The More You Know, The More You Know You Don’t Know - Project Zero↗2022-04-01
▶
Project0
Racing against the clock -- hitting a tiny kernel race window - Project Zero↗2022-03-01
▶

📋Vendor Advisories

8
Ubuntu
Linux kernel vulnerabilities↗2025-08-27
▶
CISA ICS
Siemens SIMATIC↗2024-03-14
▶
Palo Alto
PAN-SA-2024-0001 Informational Bulletin: Impact of OSS CVEs in PAN-OS↗2024-02-14
▶
CISA
Android Kernel Race Condition Vulnerability↗2022-05-23
▶
Ubuntu
Linux kernel vulnerabilities↗2022-04-01
▶

📐Framework References

2
CWE
Use After Free↗
▶
CWE
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')↗
▶