CVE-2021-28310 — Windows 10 20h2
HIGHCVE-2021-28310 is a high-severity (CVSS 7.8) Out-of-bounds Write vulnerability in microsoft windows 10 20h2. It is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
Win32k Elevation of Privilege Vulnerability
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2021-11-03. Federal agencies were required to remediate by 2021-11-17.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2021-28310.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-28310 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Win32k Elevation of Privilege Vulnerability
Affected Products
windows 10 20h2microsoftwindows 10 1803microsoftwindows 10 1809microsoftwindows 10 1909microsoftwindows 10 2004microsoftwindows server 20h2microsoftResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft windows 10 20h2 deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2021-28310 yet — track the microsoft windows 10 20h2 advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2021-28310 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.