Security readout for executives and security teams
Plain-English summary
This flaw lets an attacker with limited access to an affected Windows machine potentially gain much greater control. It is not a remote, unauthenticated entry point, but it can turn an initial foothold into a serious compromise. CISA’s KEV listing confirms exploitation has occurred, making delayed remediation a material business risk.
Executive priority
Treat this as a high-priority remediation item because exploitation is documented and successful abuse could severely affect confidentiality, integrity, and availability. Require accountable patch verification across affected endpoints and servers. Escalate unsupported or otherwise unpatchable systems for risk reduction and replacement planning using Microsoft guidance.
Technical view
CVE-2021-43226 is an elevation-of-privilege vulnerability in the Windows Common Log File System driver. Its CVSS 3.1 score is 7.8: local access, low complexity, low privileges, no user interaction, unchanged scope, and high confidentiality, integrity, and availability impacts. The supplied sources provide no CWE or root-cause details.
Likely exposure
Likely exposure exists on unremediated systems running the listed Windows releases, spanning Windows 7, 8.1, 10, 11, and several Windows Server versions. Exploitation requires local access and low privileges, making this principally a post-compromise privilege-escalation risk rather than a direct remote entry point.
Exploitation context
CISA includes this CVE in its Known Exploited Vulnerabilities catalog, establishing exploitation in the wild. The bundle does not identify campaign attribution, exploitation chronology, current activity, or public proof-of-concept status. Because local access is required, attackers would generally need an existing foothold or legitimate low-privilege account.
Researcher notes
The bundle contains no CWE, root-cause detail, exploit technique, indicators, or named patch KBs. Some embedded CPE labels appear inconsistent with their stated product releases, so they should not be treated as authoritative patch boundaries. Validate affectedness and fixed builds directly against MSRC. KEV establishes historical exploitation evidence, not current campaign activity or public exploit availability.
Mitigation direction
- Review the Microsoft advisory and install the applicable security update for each affected Windows release.
- Prioritize high-value and broadly accessed Windows endpoints and servers where local footholds could be amplified.
- If immediate updating is impossible, use only mitigations explicitly provided by Microsoft; none are supplied in this bundle.
- Track remediation under the organization’s KEV process until every affected asset is verified.
Validation and detection
- Inventory Windows editions, versions, architectures, and build numbers; compare them with the bundle’s affected-product list.
- Use Microsoft’s advisory to map each asset to its applicable update and confirm installation through trusted patch records.
- Rescan patched systems and investigate discrepancies between scanner findings, installed builds, and Microsoft applicability guidance.
- Review endpoint telemetry for suspicious local privilege-escalation activity; the bundle supplies no CVE-specific indicators.
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
SSVC decision data
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:C1.85.9microsoftVulnerability 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
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2021-43226 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2025-10-06T00:00:00.000Z: CVE-2021-43226 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43226CVE reference, microsoft · x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-43226CVE reference, CISA-ADP · 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.