medium 6.4

CVE-2021-0920 kev in the critical feed json

In unix_scm_to_skb of af_unix.c, there is a possible use after free bug due to a race condition.

published 2021-12-15 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-3539

cvss: 6.4; version 3.1, CNA
cisa kev: Exploited; added 2022-05-23
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 58%
public exploits: 0; none known

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

Patch / fix

cisa required action Apply updates per vendor instructions.

distros 6

debian ubuntu red hat suse opensuse rocky linux

linux Debian 14, Debian 13, Debian 12 5.14.6-1

debian advisories DEBIAN-CVE-2021-0920

linux Ubuntu 18.04 LTS 4.15.0-159.167
linux Ubuntu 20.04 LTS 5.4.0-88.99
linux-aws Ubuntu 18.04 LTS 4.15.0-1112.119
linux-aws Ubuntu 20.04 LTS 5.4.0-1057.60
linux-gcp Ubuntu 20.04 LTS 5.4.0-1053.57
linux-gke Ubuntu 20.04 LTS 5.4.0-1053.56
linux-ibm Ubuntu 20.04 LTS 5.4.0-1005.6
linux-kvm Ubuntu 18.04 LTS 4.15.0-1100.102

ubuntu advisories UBUNTU-CVE-2021-0920

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

redhat-virtualization-host RHEL 7 4.3.22-20220330.1.el7_9
redhat-virtualization-host-image-update RHEL 7 4.3.22-20220330.1.el7_9
kernel RHEL 8 4.18.0-348.20.1.el8_5
perf RHEL 8 4.18.0-348.20.1.el8_5
bpftool RHEL 8 4.18.0-348.20.1.el8_5
kernel-core RHEL 8 4.18.0-348.20.1.el8_5
kernel-tools RHEL 8 4.18.0-348.20.1.el8_5
python3-perf RHEL 8 4.18.0-348.20.1.el8_5

red hat advisories RHSA-2022:1263 RHSA-2022:0825 RHSA-2022:0777 RHSA-2022:1373 RHSA-2022:1324 RHSA-2022:1103

kernel-rt SLE Micro 5.0, Real Time Module 15 SP2 5.3.18-150200.79.2
kernel-syms-rt Real Time Module 15 SP2 5.3.18-150200.79.1
kernel-rt_debug Real Time Module 15 SP2 5.3.18-150200.79.2
kernel-source-rt Real Time Module 15 SP2 5.3.18-150200.79.2
kernel-syms SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +7 more 5.3.18-150200.24.112.1
kernel-source SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +7 more 5.3.18-150200.24.112.1
kernel-default SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +10 more 5.3.18-150200.24.112.1
kernel-preempt SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLES 15 SP2-BCL +7 more 5.3.18-150200.24.112.1

suse advisories SUSE-SU-2026:0688-1 SUSE-SU-2022:1257-1 SUSE-SU-2022:1197-1 SUSE-SU-2022:1039-1 SUSE-SU-2022:1038-1 SUSE-SU-2022:1037-1

dtb-aarch64 openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-64kb openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-syms openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-obs-qa openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-source openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-default openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-preempt openSUSE Leap 15.3 5.3.18-150300.59.60.4
kernel-kvmsmall openSUSE Leap 15.3 5.3.18-150300.59.60.4

opensuse advisories openSUSE-SU-2022:1039-1 openSUSE-SU-2022:1037-1 openSUSE-SU-2022:0366-1

kernel Rocky Linux 8 4.18.0-348.20.1.el8_5
kernel-rt Rocky Linux 8 4.18.0-348.20.1.rt7.150.el8_5

rocky linux advisories RLSA-2022:0825 RLSA-2022:0819

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-0920 updated 2026-11-07 cvss 7.4

kernel: Use After Free in unix_gc() which could result in a local privilege escalation

Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-348.20.1.el8_5, kernel-debuginfo-common-aarch64 4.18.0-348.20.1.el8_5, kernel-debuginfo-common-ppc64le 4.18.0-348.20.1.el8_5
fixed: vendor fix RHSA-2022:0825
Red Hat CodeReady Linux Builder EUS (v. 8.2) kernel-debuginfo-common-x86_64 4.18.0-193.75.1.el8_2, kernel-debuginfo-common-aarch64 4.18.0-193.75.1.el8_2, kernel-debuginfo-common-ppc64le 4.18.0-193.75.1.el8_2
fixed: vendor fix RHSA-2022:0636
Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-348.20.1.el8_5, kernel 4.18.0-348.20.1.el8_5, bpftool 4.18.0-348.20.1.el8_5, kpatch-patch-4_18_0-348 1-3.el8, kernel-core 4.18.0-348.20.1.el8_5, kernel-tools 4.18.0-348.20.1.el8_5, +19 more
fixed: vendor fix RHSA-2022:0825
Red Hat Enterprise Linux BaseOS E4S (v. 8.1) perf 4.18.0-147.64.1.el8_1, kernel 4.18.0-147.64.1.el8_1, bpftool 4.18.0-147.64.1.el8_1, kernel-core 4.18.0-147.64.1.el8_1, kernel-tools 4.18.0-147.64.1.el8_1, python3-perf 4.18.0-147.64.1.el8_1, +19 more
fixed: vendor fix RHSA-2022:0823
Red Hat Enterprise Linux BaseOS EUS (v. 8.2) perf 4.18.0-193.75.1.el8_2, kernel 4.18.0-193.75.1.el8_2, bpftool 4.18.0-193.75.1.el8_2, kernel-core 4.18.0-193.75.1.el8_2, kernel-tools 4.18.0-193.75.1.el8_2, python3-perf 4.18.0-193.75.1.el8_2, +25 more
fixed: vendor fix RHSA-2022:0636
Red Hat Enterprise Linux BaseOS EUS (v.8.4) perf 4.18.0-305.40.1.el8_4, kernel 4.18.0-305.40.1.el8_4, bpftool 4.18.0-305.40.1.el8_4, kpatch-patch-4_18_0-305 1-11.el8, kernel-core 4.18.0-305.40.1.el8_4, kernel-tools 4.18.0-305.40.1.el8_4, +26 more
fixed: vendor fix RHSA-2022:0777
Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, kernel-tools-libs 3.10.0-1160.59.1.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7
fixed: vendor fix RHSA-2022:0620
Red Hat Enterprise Linux CRB EUS (v.8.4) kernel-debuginfo-common-x86_64 4.18.0-305.40.1.el8_4, kernel-debuginfo-common-aarch64 4.18.0-305.40.1.el8_4, kernel-debuginfo-common-ppc64le 4.18.0-305.40.1.el8_4
fixed: vendor fix RHSA-2022:0777

show 29 more

Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.59.1.rt56.1200.el7
fixed: vendor fix RHSA-2022:0622
Red Hat Enterprise Linux for Real Time (v. 8) kernel-rt 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules-extra 4.18.0-348.20.1.rt7.150.el8_5, +2 more
fixed: vendor fix RHSA-2022:0819
Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debug-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.59.1.rt56.1200.el7
fixed: vendor fix RHSA-2022:0622
Red Hat Enterprise Linux NFV EUS (v.8.4) kernel-rt 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-kvm 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-core 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-modules 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-debug-kvm 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-debug-core 4.18.0-305.40.1.rt7.112.el8_4, +4 more
fixed: vendor fix RHSA-2022:0771
Red Hat Enterprise Linux Real Time EUS (v. 8.2) kernel-rt 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-core 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-modules 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-debug-core 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-debug-modules 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-modules-extra 4.18.0-193.75.1.rt13.125.el8_2, +2 more
fixed: vendor fix RHSA-2022:0629
Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-kvm 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-core 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-modules 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-kvm 4.18.0-348.20.1.rt7.150.el8_5, kernel-rt-debug-core 4.18.0-348.20.1.rt7.150.el8_5, +4 more
fixed: vendor fix RHSA-2022:0819
Red Hat Enterprise Linux Real Time for NFV EUS (v. 8.2) kernel-rt 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-kvm 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-core 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-modules 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-debug-kvm 4.18.0-193.75.1.rt13.125.el8_2, kernel-rt-debug-core 4.18.0-193.75.1.rt13.125.el8_2, +4 more
fixed: vendor fix RHSA-2022:0629
Red Hat Enterprise Linux RT EUS (v.8.4) kernel-rt 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-core 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-modules 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-debug-core 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-debug-modules 4.18.0-305.40.1.rt7.112.el8_4, kernel-rt-modules-extra 4.18.0-305.40.1.rt7.112.el8_4, +2 more
fixed: vendor fix RHSA-2022:0771
Red Hat Enterprise Linux Server (v. 6 ELS) perf 2.6.32-754.47.1.el6, kernel 2.6.32-754.47.1.el6, kernel-kdump 2.6.32-754.47.1.el6, kernel-firmware 2.6.32-754.47.1.el6, kernel-abi-whitelists 2.6.32-754.47.1.el6, kernel-debuginfo-common-i686 2.6.32-754.47.1.el6, +2 more
fixed: vendor fix RHSA-2022:1417
Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-kdump 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, +17 more
fixed: vendor fix RHSA-2022:0620
Red Hat Enterprise Linux Server AUS (v. 7.3) perf 3.10.0-514.99.1.el7, kernel 3.10.0-514.99.1.el7, python-perf 3.10.0-514.99.1.el7, kernel-tools 3.10.0-514.99.1.el7, kernel-tools-libs 3.10.0-514.99.1.el7, kernel-abi-whitelists 3.10.0-514.99.1.el7, +1 more
fixed: vendor fix RHSA-2022:1106
Red Hat Enterprise Linux Server AUS (v. 7.4) perf 3.10.0-693.99.1.el7, kernel 3.10.0-693.99.1.el7, python-perf 3.10.0-693.99.1.el7, kernel-tools 3.10.0-693.99.1.el7, kernel-tools-libs 3.10.0-693.99.1.el7, kernel-abi-whitelists 3.10.0-693.99.1.el7, +1 more
fixed: vendor fix RHSA-2022:1104
Red Hat Enterprise Linux Server AUS (v. 7.6) perf 3.10.0-957.92.1.el7, kernel 3.10.0-957.92.1.el7, bpftool 3.10.0-957.92.1.el7, python-perf 3.10.0-957.92.1.el7, kernel-tools 3.10.0-957.92.1.el7, kernel-tools-libs 3.10.0-957.92.1.el7, +2 more
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server AUS (v. 7.7) perf 3.10.0-1062.66.1.el7, kernel 3.10.0-1062.66.1.el7, bpftool 3.10.0-1062.66.1.el7, python-perf 3.10.0-1062.66.1.el7, kernel-tools 3.10.0-1062.66.1.el7, kernel-tools-libs 3.10.0-1062.66.1.el7, +2 more
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Server E4S (v. 7.6) perf 3.10.0-957.92.1.el7, kernel 3.10.0-957.92.1.el7, python-perf 3.10.0-957.92.1.el7, kernel-tools 3.10.0-957.92.1.el7, kpatch-patch-3_10_0-957_72_1 1-6.el7, kpatch-patch-3_10_0-957_76_1 1-6.el7, +10 more
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server E4S (v. 7.7) perf 3.10.0-1062.66.1.el7, kernel 3.10.0-1062.66.1.el7, bpftool 3.10.0-1062.66.1.el7, python-perf 3.10.0-1062.66.1.el7, kernel-tools 3.10.0-1062.66.1.el7, kpatch-patch-3_10_0-1062_49_1 1-6.el7, +12 more
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Server Optional (v. 6 ELS) python-perf 2.6.32-754.47.1.el6, kernel-debuginfo-common-i686 2.6.32-754.47.1.el6, kernel-debuginfo-common-s390x 2.6.32-754.47.1.el6, kernel-debuginfo-common-x86_64 2.6.32-754.47.1.el6
fixed: vendor fix RHSA-2022:1417
Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.59.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.59.1.el7
fixed: vendor fix RHSA-2022:0620
Red Hat Enterprise Linux Server Optional AUS (v. 7.3) kernel-debuginfo-common-x86_64 3.10.0-514.99.1.el7
fixed: vendor fix RHSA-2022:1106
Red Hat Enterprise Linux Server Optional AUS (v. 7.4) kernel-debuginfo-common-x86_64 3.10.0-693.99.1.el7
fixed: vendor fix RHSA-2022:1104
Red Hat Enterprise Linux Server Optional AUS (v. 7.6) kernel-debuginfo-common-x86_64 3.10.0-957.92.1.el7
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server Optional AUS (v. 7.7) kernel-debuginfo-common-x86_64 3.10.0-1062.66.1.el7
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Server Optional E4S (v. 7.6) kernel-debuginfo-common-x86_64 3.10.0-957.92.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-957.92.1.el7
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server Optional E4S (v. 7.7) kernel-debuginfo-common-x86_64 3.10.0-1062.66.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1062.66.1.el7
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Server Optional TUS (v. 7.6) kernel-debuginfo-common-x86_64 3.10.0-957.92.1.el7
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server Optional TUS (v. 7.7) kernel-debuginfo-common-x86_64 3.10.0-1062.66.1.el7
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Server TUS (v. 7.6) perf 3.10.0-957.92.1.el7, kernel 3.10.0-957.92.1.el7, bpftool 3.10.0-957.92.1.el7, python-perf 3.10.0-957.92.1.el7, kernel-tools 3.10.0-957.92.1.el7, kernel-tools-libs 3.10.0-957.92.1.el7, +2 more
fixed: vendor fix RHSA-2022:1107
Red Hat Enterprise Linux Server TUS (v. 7.7) perf 3.10.0-1062.66.1.el7, kernel 3.10.0-1062.66.1.el7, bpftool 3.10.0-1062.66.1.el7, python-perf 3.10.0-1062.66.1.el7, kernel-tools 3.10.0-1062.66.1.el7, kernel-tools-libs 3.10.0-1062.66.1.el7, +2 more
fixed: vendor fix RHSA-2022:1324
Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, kernel-tools-libs 3.10.0-1160.59.1.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7
fixed: vendor fix RHSA-2022:0620

3 more fixed, 3 more not affected in the full advisory

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-24-074-07 updated 2024-03-14 cvss 6.4

Siemens SIMATIC

Siemens SIMATIC RF160B (6GT2003-0FA00) <V2.2
affected: mitigation “Siemens has released a new version (V2.2) for SIMATIC RF160B and recommends to update to the latest version.” siemens.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Timeline

2021-11-05 0-day patched (Project Zero)
2021-12-15 Published
2022-05-23 Added to CISA KEV
2022-06-13 CISA patch deadline
2024-02-06 CISA SSVC: exploitation active

Known exploited

Added: 4 y ago (2022-05-23)
Patch by: 2022-06-13 (4 y ago)
Ransomware: Not known
Required action: Apply updates per vendor instructions.
Vendor, product: Android, Kernel
CISA name: Android Kernel Race Condition Vulnerability

Zero-day

Detected in real attacks while still unknown to the vendor and the public, per Google Project Zero's 0day In-the-Wild tracker.

Patched: 2021-11-05
Details: project zero root cause analysis

CISA SSVC

Exploitation: Active, exploited in the wild
Automatable: no
Technical impact: total
Assessed: 2 y ago (2024-02-06)

Exploit prediction

0.87% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.4	CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	3.1	6.4	CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
CNA	3.1	6.4	CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.9	AV:L/AC:M/Au:N/C:C/I:C/A:C

Affected products

n/a Android

Classification

Weakness

CWE-416 Use After Free
CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization

Technology feeds

Linux kernel rss critical rss

References

source.android.com /security/bulletin/2021-11-01
vendor-advisory
lists.debian.org /debian-lts-announce/2021/12/msg00012.html
mailing-list, third-party-advisory
cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920
government-resource, third-party-advisory, us-government-resource

Sources

CVE List CVE-2021-0920
NVD CVE-2021-0920

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary