How severe is CVE-2026-68820?

CVE-2026-68820 has a CVSS score of 7/10, rated HIGH. Immediate patching is strongly recommended.

Which products are affected by CVE-2026-68820?

CVE-2026-68820 affects the following products: microsoft windows 10 21h2, microsoft windows 10 22h2, microsoft windows 10 1607, microsoft windows 10 1809, microsoft windows 11 23h2, microsoft windows 11 24h2, microsoft windows 11 25h2, microsoft windows 11 26h1, and 5 more.

How do I patch CVE-2026-68820?

Apply the microsoft windows 10 21h2 security patch or hotfix for CVE-2026-68820 on the affected version, following the vendor advisory for your exact build.

How do I detect CVE-2026-68820 across my infrastructure?

Inventory every microsoft windows 10 21h2 deployment and check each version against the affected-products list above.

How do I mitigate CVE-2026-68820 if there is no patch (or I can't update yet)?

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.

Is CVE-2026-68820 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-68820 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-68820?

CVE-2026-68820 has an EPSS (Exploit Prediction Scoring System) score of 8.6%, placing it in the 95th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2026-68820 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-68820 (Microsoft Windows Ancillary Function Driver for WinSock Use-After-Free Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-08-11. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-08-25. The required action was: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-68820?

CVE-2026-68820 is classified as Use After Free (CWE-416). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2026-68820?

CVE-2026-68820 affects microsoft windows 10 21h2; microsoft windows 10 22h2; microsoft windows 10 1607; microsoft windows 10 1809, and 9 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2026-68820 published, and has it been updated?

CVE-2026-68820 was published on August 11, 2026 and was last updated on October 26, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

CISA KEV · ACTIVELY EXPLOITED

HIGH severity

CVE-2026-68820 — Microsoft Windows 10 21h2

HIGH

CVE-2026-68820 is a high-severity (CVSS 7) Use After Free vulnerability in microsoft windows 10 21h2. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-08-11) — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Published

Aug 11, 2026

Updated

Oct 26, 2026

Affected

13 products

Patched

See advisory

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-08-11. Federal agencies were required to remediate by 2026-08-25.
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-2026-68820.

EPSS Exploitation Probability

via FIRST.org ↗

8.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs95th percentile — riskier than 95% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Description

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Affected Products

13 products · 16 configurations

windows 10 21h2microsoft

< 10.0.19044.7663

range

windows 10 22h2microsoft

< 10.0.19045.7663

range

windows 10 1607microsoft

< 10.0.14393.9418

range

windows 10 1809microsoft

< 10.0.17763.9115

range

windows 11 23h2microsoft

< 10.0.22631.7517

range

windows 11 24h2microsoft

< 10.0.26100.9106

range

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every microsoft windows 10 21h2 deployment and check each version against the affected-products list above.
Fix
Apply the microsoft windows 10 21h2 security patch or hotfix for CVE-2026-68820 on the affected version, following the vendor advisory for your exact build.
Workarounds
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

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

O3 Security · Runtime Protection

Is CVE-2026-68820 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works

CVSS Score

7/10CVSS v3 base

Vector breakdown

Attack Vector

Local

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE Classification

CWE-416Use After Free

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

Timeline

KEV added

Aug 11, 2026

Disclosed

Aug 11, 2026

Last updated

Oct 26, 2026

Identifiers

CVE-2026-68820

References

Fixmsrc.microsoft.com · CVE 2026 68820 Webcisa.gov · known exploited vulnerabilities catalog

Related vulnerabilities

This CVE is high severity; 4 of 8 other CVEs with CWE-416 are rated as high or higher (top: high).

CVE-2026-126064CVE-2026-114613CVE-2026-96889CVE-2026-112396CVE-2026-112402CVE-2026-85790GHSA-wq5f-xc86-pv6wGHSA-mwm8-39rw-8826Browse all CWE-416

Provenance

Sources

OSV.devNVDCISA KEVFIRST.org (EPSS)

Last verifiedOct 26, 2026

CVE-2026-68820 — Microsoft Windows 10 21h2

Exploitation Status

Actively exploited in the wild

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Description

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2026-68820 being exploited in your environment?