High · published January 13, 2026
⚡ A sneaky race condition is hiding in the Windows Ancillary Function Driver for WinSock! An authorized attacker could escalate privileges without breaking a sweat.🔍 Think of it like a game of tag where one player checks in with the rules, but the other player has already crossed the finish line before the rules are even enforced. The attacker is exploiting a timing window, making it seem like everything’s fine right up until they seize the victory! If an attacker takes advantage of this race condition, they could elevate their privileges locally, gaining access to sensitive areas of the system that should remain locked up tight. This could lead to unauthorized changes, data theft, or even a full-blown system takeover. Definitely not a scenario you want to find yourself in!
Think of it like a game of tag where one player checks in with the rules, but the other player has already crossed the finish line before the rules are even enforced. The attacker is exploiting a timing window, making it seem like everything’s fine right up until they seize the victory! The CVE-2026-20831 vulnerability is a time-of-check to time-of-use (TOCTOU) race condition in the Windows Ancillary Function Driver for WinSock. It allows an authorized attacker to exploit the timing difference between checking permissions and using those permissions to execute further commands.
If an attacker takes advantage of this race condition, they could elevate their privileges locally, gaining access to sensitive areas of the system that should remain locked up tight. This could lead to unauthorized changes, data theft, or even a full-blown system takeover. Definitely not a scenario you want to find yourself in! To mitigate this issue, ensure your systems are updated by applying the latest security patches released by Microsoft. Regularly audit your user permissions to ensure compliance and monitor for any unauthorized changes. Don't wait – secure your systems now! This is fixable! Stay proactive, follow these steps, and you’ll keep those digital doors locked tight! 🛡️
| Product | Versions | Fixed in |
|---|---|---|
| microsoft/windows_10_1607 | < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft/windows_10_1607 | < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft/windows_10_1809 | < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft/windows_10_1809 | < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft/windows_10_21h2 | < 10.0.19044.6809 | 10.0.19044.6809 |
| microsoft/windows_10_22h2 | < 10.0.19045.6809 | 10.0.19045.6809 |
| microsoft/windows_11_23h2 | < 10.0.22631.6491 | 10.0.22631.6491 |
| microsoft/windows_11_24h2 | < 10.0.26100.7623 | 10.0.26100.7623 |
| microsoft/windows_11_25h2 | < 10.0.26200.7623 | 10.0.26200.7623 |
| microsoft/windows_server_2008 | all versions | — |
| microsoft/windows_server_2008 | all versions | — |
| microsoft/windows_server_2008 | all versions | — |
| microsoft/windows_server_2012 | all versions | — |
| microsoft/windows_server_2012 | all versions | — |
| microsoft/windows_server_2016 | < 10.0.14393.8783 | 10.0.14393.8783 |
| microsoft/windows_server_2019 | < 10.0.17763.8276 | 10.0.17763.8276 |
| microsoft/windows_server_2022 | < 10.0.20348.4648 | 10.0.20348.4648 |
| microsoft/windows_server_2022_23h2 | < 10.0.25398.2092 | 10.0.25398.2092 |
| microsoft/windows_server_2025 | < 10.0.26100.32230 | 10.0.26100.32230 |