CVE-2021-34486: Microsoft Windows Event Tracing Privilege Escalation Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 28 Mar 2022, 228 days after the CVE record was published.

How likely is exploitation in the next 30 days?

9.3%

EPSS score, percentile 95.4 of all scored records

How severe?

7.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

Required action (CISA), due 18 Apr 2022: Apply updates per vendor instructions.

Advisories and patches (1)

Which versions are affected?

Affected: 10.0.17763.0 up to, not including, 10.0.17763.2114; 10.0.0 up to, not including, 10.0.17763.2114; 10.0.0 up to, not including, 10.0.18363.1734; 10.0.0 up to, not including, 10.0.19041.1165; 10.0.0 up to, not including, 10.0.19042.1165; 10.0.0 up to, not including, 10.0.19043.1165; 10.0.17763.0 up to, not including, 10.0.17763.2114; 10.0.17763.0 up to, not including, 10.0.17763.2114; 10.0.0 up to, not including, 10.0.19041.1165; 10.0.0 up to, not including, 10.0.19042.1165

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 18 April 2022.

Advisories and patches

• Windows Event Tracing Elevation of Privilege Vulnerability (Vendor advisory, Patch)

Linked from CISA's catalog entry

• https://nvd.nist.gov/vuln/detail/CVE-2021-34486

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Microsoft Windows Event Tracing contains an unspecified vulnerability which can allow for privilege escalation.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2021-34486 to its Known Exploited Vulnerabilities (KEV) catalog on 28 Mar 2022.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 18 Apr 2022.
• The CVE record was published on 12 Aug 2021, 228 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.8 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 9.3% (percentile 95.4), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Windows Event Tracing Elevation of Privilege Vulnerability

Windows Event Tracing Elevation of Privilege Vulnerability

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-416: Use After Free

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

More exploited Microsoft vulnerabilities

• CVE-2026-96951: Microsoft Windows Command Injection Vulnerability (added 13 Oct 2026)
• CVE-2026-65660: Microsoft SharePoint Code Injection Vulnerability (added 25 Sep 2026)
• CVE-2026-81963: Microsoft Windows Link Following Vulnerability (added 8 Sep 2026)
• CVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerability (added 8 Sep 2026)
• CVE-2019-1068: Microsoft SQL Server Remote Code Execution Vulnerability (added 26 Aug 2026)
• CVE-2026-33824: Microsoft Internet Key Exchange (IKE) Service Extensions Double Free Vulnerability (added 18 Aug 2026)