CVE-2026-68820
CVE-2026-68820 is a security flaw in Microsoft Windows Ancillary Function Driver for WinSock, a part of Windows, Microsoft’s operating system. Someone who already has a foothold can use Microsoft Windows Ancillary Function Driver for WinSock to take full control of the machine. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 11 Aug 2026.[1]
Microsoft Windows Ancillary Function Driver for WinSock is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Fixed in version 10.0.14393.9418, 10.0.17763.9121, 10.0.19044.7663 and 10.0.19045.7663 and others.
Description
CISA calls it an use-after-free in Microsoft Windows Ancillary Function Driver for WinSock. In its words: “Microsoft Windows Ancillary Function Driver for WinSock contains a use-after-free vulnerability that allows an authorized attacker to elevate privileges locally.”[1]
The underlying weakness is use after free (CWE-416), in MITRE’s list of common software weaknesses.[2]
It scores 7.0 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| Windows 10 Version 1607 | 10.0.14393.9418 |
| Windows 10 Version 1809 | 10.0.17763.9121 |
| Windows 10 Version 21H2 | 10.0.19044.7663 |
| Windows 10 Version 22H2 | 10.0.19045.7663 |
| Windows 11 version 23H2 | 10.0.22631.7517 |
| Windows 11 Version 23H2 | 10.0.22631.7517 |
| Windows 11 Version 24H2 | 10.0.26100.9168 |
| Windows 11 Version 25H2 | 10.0.26200.9168 |
Every device with Microsoft Windows Ancillary Function Driver for WinSock needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 11 Aug 2026, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 25 Aug 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 9%. That’s in the top 5% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “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).”[1]
- Update Microsoft Windows Ancillary Function Driver for WinSock now.On Windows: Settings, Windows Update, Check for updates, then restart. Office updates come the same way, or from any Office app: File, Account, Update Options. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 10.0.14393.9418 or later.Fixed in version 10.0.14393.9418, 10.0.17763.9121, 10.0.19044.7663 and 10.0.19045.7663 and others. Anything older is what attackers are going after.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.0.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 9%.[4] |
See also
Other Microsoft flaws
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
- CVE-2026-81963, Microsoft Windows: link following ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
Other use after free flaws
- CVE-2026-109619, PHP: stale internal request-state ·
- CVE-2026-109618, PHP: memory corruption ·
- CVE-2020-9715, Adobe Acrobat: use-after-free ·
- CVE-2026-5281, Google Dawn: use-after-free ·
- CVE-2023-43000, Apple devices: use-after-free ·
Added the same day
- CVE-2026-72898, Metabase: SQL injection ·
- CVE-2026-20349, Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD): heap inspection ·
Every Microsoft flaw on CISA’s list · Everything added in August 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Windows Ancillary Function Driver for WinSock Use-After-Free Vulnerability”. Known Exploited Vulnerabilities Catalog, added 11 Aug 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-68820 Detail”. National Vulnerability Database, published 11 Aug 2026.
- ^ Microsoft. Advisories and fixes: portal.msrc.microsoft.com, msrc.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.086, percentile 95.1, 31 Oct 2026.
- CVE Program. “CVE-2026-68820”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.