Security readout for executives and security teams
Plain-English summary
CVE-2021-43226 lets an already-authenticated attacker or malware on a Windows system raise privileges through the Common Log File System driver. It is not a remote entry point, but it can turn limited access into full system compromise. CISA lists it as known exploited.
Executive priority
Patch promptly as a high-priority Windows fleet issue. KEV status means exploitation has been observed, and the flaw can convert a limited local foothold into broad system control. It should be managed as urgent patch compliance, especially on workstations and shared servers.
Technical view
This is a Windows CLFS driver elevation-of-privilege flaw with CVSS 3.1 score 7.8: local attack vector, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact. The source bundle identifies many Windows client and server versions as affected.
Likely exposure
Exposure is likely on unpatched Windows endpoints and servers listed in the bundle, including Windows 7, 8.1, 10, 11, and Windows Server 2008, 2016, 2019, and 2022 variants. Risk is highest where attackers can gain any local foothold first.
Exploitation context
Active exploitation is supported by CISA KEV status. The bundle does not describe exploitation mechanics, public exploit availability, attacker groups, or campaign details. Treat this as a post-compromise privilege escalation issue that can help intruders deepen access.
Researcher notes
The bundle provides CVSS, affected products, MSRC, and CISA KEV references, but no CWE, root-cause detail, exploit narrative, or specific KB mapping. Some CPE entries appear inconsistent, so validate exposure using Microsoft guidance and observed OS build data, not CPE strings alone.
Mitigation direction
- Apply Microsoft security updates or vendor-directed remediation for affected Windows versions.
- Prioritize assets in CISA KEV-driven patch compliance programs.
- Reduce local administrative access and remove unnecessary interactive logon rights.
- Investigate vendor guidance before relying on any workaround not named in sources.
Validation and detection
- Inventory Windows versions and builds against the affected products in the source bundle.
- Confirm installed Microsoft updates using MSRC guidance for CVE-2021-43226.
- Check vulnerability scanner results for CVE-2021-43226 across endpoints and servers.
- Review EDR alerts for suspicious local privilege escalation activity on unpatched hosts.
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.
Privilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-43226 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
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- Yes
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
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:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C1.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226CVE reference · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226CVE 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.