CVE-2021-28310: Microsoft Win32k Privilege Escalation Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, 204 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 8.4%
EPSS score, percentile 95 of all scored records
- How severe?
- 7.8 High
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA deadline 17 Nov 2021. Apply updates per vendor instructions.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 10.0.0
- 10.0.0
- 10.0.0
- 10.0.0
- 10.0.0
- 10.0.0
and 4 more in the table below
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
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 17 November 2021.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
| Status | Versions |
|---|---|
| Affected | 10.0.0 |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Microsoft Windows Win32k contains an unspecified vulnerability that allows for privilege escalation.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2021-28310 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Nov 2021.
- 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 17 Nov 2021.
- The CVE record was published on 13 Apr 2021, 204 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 8.4% (percentile 95), 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
Win32k Elevation of Privilege Vulnerability
Win32k 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-787: Out-of-bounds Write
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 13 Apr 2021 | CVE record published |
| 3 Nov 2021 | Added to CISA KEV |
| 17 Nov 2021 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
References
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