Security readout for executives and security teams
Plain-English summary
CVE-2021-0920 is an Android kernel use-after-free race condition that can let a local attacker raise privileges. The published scoring is medium because exploitation needs high privileges and high complexity, but CISA KEV listing means defenders should treat it as operationally urgent where affected kernels remain unpatched.
Executive priority
Treat as priority remediation for affected Android and Linux kernel assets because KEV status confirms real-world exploitation. Risk is highest where local privileged users, shared devices, or high-value endpoints exist. Unsupported devices should be isolated, replaced, or formally risk-accepted.
Technical view
The flaw is in unix_scm_to_skb in af_unix.c and is classified as CWE-416. Sources describe local escalation of privilege, no user interaction, and potential high impact to confidentiality, integrity, and availability. A Debian LTS Linux security update is referenced, indicating kernel backport relevance beyond Android-specific device tracking.
Likely exposure
Most likely exposure is Android devices or Linux systems running affected kernel builds without the vendor security update. Evidence in the bundle names Android kernel and a Debian LTS Linux update, but does not enumerate specific device models, kernel versions, or OEM patch levels.
Exploitation context
Active exploitation is supported by the CISA Known Exploited Vulnerabilities listing. Public source details indicate local attack vector, high attack complexity, high privileges required, and no user interaction. The bundle does not provide exploit mechanics, public exploit maturity, or campaign details.
Researcher notes
The source bundle is enough to confirm vulnerability class, affected Android kernel scope, CVSS 6.4, and KEV status. It is not enough to identify exact upstream commit, affected kernel version ranges, OEM model coverage, or exploit details. Validate with vendor-specific kernel changelogs before declaring systems fixed.
Mitigation direction
- Apply Android or OEM security updates covering the November 2021 bulletin.
- For Debian LTS systems, apply the DLA 2843-1 Linux security update.
- Check vendor kernel advisories for fixed builds and backports.
- Prioritize remediation for internet-managed, shared, or high-value endpoint fleets.
- Restrict unnecessary local privileged access until patching is confirmed.
Validation and detection
- Inventory Android devices and Linux kernels in scope.
- Confirm Android security patch level or OEM kernel build includes the fix.
- Verify Debian systems have the DLA 2843-1 fixed Linux package installed.
- Check CISA KEV tracking for required remediation handling.
- Record unsupported devices that cannot receive vendor fixes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-0920 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.4 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H0.55.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.4MediumVector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://source.android.com/security/bulletin/2021-11-01CVE reference · x_refsource_MISC
- [debian-lts-announce] 20211216 [SECURITY] [DLA 2843-1] linux security updateCVE reference · mailing-list, x_refsource_MLIST
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-0920CVE reference · government-resource
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.