Security readout for executives and security teams
Plain-English summary
This Windows flaw lets a user who already has limited local access gain higher privileges. It can turn an initial foothold into broad control of a workstation or server. CISA’s Known Exploited Vulnerabilities listing confirms exploitation has occurred, making prompt remediation important.
Executive priority
Treat this as a high-priority patching item because exploitation is documented and successful abuse can provide extensive system control. Prioritize exposed servers, administrator workstations, shared systems, and assets where attackers could obtain local access. Track exceptions until Microsoft-supported remediation is verified.
Technical view
CVE-2021-36955 is an elevation-of-privilege vulnerability in the Windows Common Log File System driver. Its CVSS 3.1 score is 7.8: local access and low privileges are required, attack complexity is low, and user interaction is unnecessary. Successful exploitation can severely affect confidentiality, integrity, and availability without changing security scope.
Likely exposure
Exposure includes the listed Windows 7, 8.1, and 10 releases and Windows Server 2008 through 2016 variants, including specified Server Core installations. Organizations should compare actual release and build information with Microsoft’s advisory because the supplied bundle does not provide complete update or file-version detection criteria.
Exploitation context
CISA includes CVE-2021-36955 in its Known Exploited Vulnerabilities catalog, supporting active-exploitation status. The vulnerability is local rather than remotely reachable by itself, so an attacker first needs low-privileged access. The supplied sources provide no campaign, malware, prevalence, or exploit-chain details.
Researcher notes
The bundle identifies the affected component and attack characteristics but supplies no CWE, root-cause analysis, vulnerable file versions, or exploit mechanics. KEV inclusion establishes exploitation, not its scale or current campaign activity. Use Microsoft’s advisory for exact applicability and update mapping; avoid inferring affected versions beyond those listed.
Mitigation direction
- Review Microsoft’s advisory for the security update applicable to each Windows release.
- Apply the applicable Microsoft security updates through established patch-management processes.
- Prioritize systems accessible to untrusted or potentially compromised local accounts.
- If patching is delayed, follow Microsoft guidance and reduce unnecessary local logon access.
Validation and detection
- Inventory Windows releases and builds against the affected-product list.
- Confirm the Microsoft update applicable to each affected release is installed.
- Re-scan patched endpoints with current authenticated vulnerability checks.
- Review endpoint telemetry for unexplained privilege elevation on previously exposed systems.
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-2021-36955 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:F/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:F/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:F/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-2021-36955 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2021-11-03T00:00:00.000Z: CVE-2021-36955 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- Windows Common Log File System Driver Elevation of Privilege VulnerabilityCVE reference, microsoft · vendor-advisory, patch
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-36955CVE reference, CVE · x_refsource_MISC, x_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-36955CVE 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.