CVE-2021-0920: Technical Deep-Dive (Auto Refreshed)

Generated on 2026-03-30T13:04:37.911Z. This file is automatically regenerated every 30 minutes by the CVE AI enrichment job using web sources (NVD, MITRE, CISA KEV, GitHub).

Executive Technical Summary

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

• Context preserved from previous revision: 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 Notes: 📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.

Technical Details

• CVE: CVE-2021-0920
• KEV date added: 2022-05-23
• KEV due date: 2022-06-13
• NVD published: 2021-12-15
• NVD modified: 2025-10-23
• MITRE modified: 2025-10-21
• CVSS base score: 6.4
• CVSS vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
• CVSS exploitability score: 0.5
• CVSS impact score: 5.9
• Attack vector: Local
• Attack complexity: High
• Privileges required: High
• User interaction: None
• Scope: Unchanged
• Confidentiality impact: High
• Integrity impact: High
• Availability impact: High

Versions and Products Impacted

• linux / linux kernel (versions: <= 5.13)
• linux / linux kernel (versions: 5.14)
• google / android
• debian / debian linux (versions: 9.0)
• n/a / Android (versions: Android kernel)

Weakness Classification

• CWE-362
• CWE-416
• Elevation of privilege

Repositories for Lab Validation (Public Examples)

• nomi-sec/PoC-in-GitHub | stars: 7605 | updated: 2026-03-30 | https://github.com/nomi-sec/PoC-in-GitHub
  Notes: 📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
• xairy/linux-kernel-exploitation | stars: 6389 | updated: 2026-03-30 | https://github.com/xairy/linux-kernel-exploitation
  Notes: A collection of links related to Linux kernel security and exploitation
• Ostorlab/KEV | stars: 608 | updated: 2026-03-23 | https://github.com/Ostorlab/KEV
  Notes: Ostorlab KEV: One-command to detect most remotely known exploitable vulnerabilities. Sourced from CISA KEV, Google's Tsunami, Ostorlab's Asteroid and Bug Bounty programs.
• DarkFunct/TK-CVE-Repo | stars: 44 | updated: 2026-03-30 | https://github.com/DarkFunct/TK-CVE-Repo
  Notes: TK-CVE-Repo

People and Organizations Mentioned

• google_android
• Android
• Kernel
• nomi-sec
• xairy
• Ostorlab
• DarkFunct

Practical Defensive Validation (Authorized Only)

1. Use only isolated environments and systems you own or are explicitly authorized to test.
2. Snapshot infrastructure before validation and preserve baseline logs (EDR, SIEM, OS, app).
3. Create low-privilege users on linux / linux kernel (versions: <= 5.13) and validate that patching blocks unauthorized admin-level actions.
4. Compare token/privilege transitions in Windows Event Logs before and after remediation.
5. Tune detections for unusual group membership changes and SYSTEM-level process launches from user sessions.

References

• NVD record: https://nvd.nist.gov/vuln/detail/CVE-2021-0920
• MITRE CVE record: https://www.cve.org/CVERecord?id=CVE-2021-0920
• CISA KEV Catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• CISA KEV JSON feed: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json
• KEV notes: https://nvd.nist.gov/vuln/detail/CVE-2021-0920
• https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html
• https://source.android.com/security/bulletin/2021-11-01
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920
• Repository example: https://github.com/nomi-sec/PoC-in-GitHub
• Repository example: https://github.com/xairy/linux-kernel-exploitation
• Repository example: https://github.com/Ostorlab/KEV
• Repository example: https://github.com/DarkFunct/TK-CVE-Repo

This content is for defensive security training and authorized validation only.