CVE-2021-0920: Android Kernel Race Condition Vulnerability
Vulnerability summary
CVE-2021-0920 is a medium (CVSS 6.9) vulnerability in Android Kernel. It is known to be exploited: CISA lists it, first on 23-05-2022. EPSS estimates a 0.87% chance of exploitation in the next 30 days, higher than 58.7% of scored vulnerabilities.
Listed as exploited by CISA (23-05-2022)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 49 · Related 24Timeline
- 15-12-2021PublishedVulnerability first disclosed.
- 23-05-2022Added to CISA KEVExploitedAndroid Kernel Race Condition Vulnerability
- 13-06-2022CISA remediation dueDeadline passedApply updates per vendor instructions.
- 21-10-2025Last modifiedVulnerability information updated.
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 metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
- NVDNIST6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.87%
Chance of exploitation in the next 30 days
Percentile
59%
Versus all other CVEs
30-day change
Increase +0.05 pp
From 0.82% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVListed- Added
- 23-05-2022
- Federal due date
- 13-06-2022
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
CISA required action
Apply updates per vendor instructions. nvd.nist.gov/vuln/detail/CVE-2021-0920
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-362Concurrent Execution using Shared Resource with Improper SynchronizationThe product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
- CWE-416Use After FreeThe product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Affected systems
Known conditions: local access, administrative account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu62 products
- linux< 3.13.0-207.258 | < 4.4.0-223.256 | < 4.15.0-159.167 | < 5.4.0-88.99
- linux-aws< 4.4.0-1103.108 | < 4.4.0-1139.153 | < 4.15.0-1112.119 | < 5.4.0-1057.60
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11< 5.11.0-1019.20~20.04.1
- linux-aws-5.3All versions (No fix recorded)
Suse34 products
- kernel-livepatch-SLE15_Update_23&distro=SUSE Linux Enterprise Live Patching 15< 15-2.2
- kernel-livepatch-SLE15_Update_24&distro=SUSE Linux Enterprise Live Patching 15< 12-2.1
- kernel-livepatch-SLE15_Update_25&distro=SUSE Linux Enterprise Live Patching 15< 9-2.1
- kernel-livepatch-SLE15_Update_26&distro=SUSE Linux Enterprise Live Patching 15< 4-2.1
- kernel-livepatch-SLE15-SP1_Update_23&distro=SUSE Linux Enterprise Live Patching 15 SP1< 15-2.2
Debian2 products
- linux< 5.14.6-1
- debian_linuxEOL9.0
Google1 product
- androidna
Linux1 product
- linux_kernel≤ 5.13 | 5.14:rc1 | 5.14:rc2 | 5.14:rc3
5 vendors · 100 products
References
15 links
lists.debian.org/debian-lts-announce/2021/12/msg00012.htmlMailing ListX Refsource MLISTThird Party Advisory- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920Government ResourceThird Party AdvisoryUS Government Resource