Is CVE-2021-31166 exploited in the wild?

Yes. CVE-2021-31166 is known to be exploited in the wild, first recorded on 6 April 2022. Treat it as urgent.

How severe is CVE-2021-31166?

Critical severity, with a CVSS score of 9.8, published 6 April 2022.

Which products and versions are affected?

Microsoft Windows 10 Version 2004 up to (excluding) 10.0.19041.982; Microsoft Windows 10 Version 20H2 up to (excluding) 10.0.19042.982; Microsoft Windows Server version 2004 up to (excluding) 10.0.19041.982; Microsoft Windows Server version 20H2 up to (excluding) 10.0.19042.982.

Is there a fix for CVE-2021-31166?

A patch was published on 2021-05-11: MSRC advisory and patch released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2021-31166 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2021-31166?

Check whether you run Microsoft HTTP Protocol Stack. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2021-31166: Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability

CVE-2021-31166 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2022-04-06

A use-after-free vulnerability in the Microsoft HTTP Protocol Stack (http.sys) allows unauthenticated remote attackers to execute arbitrary code on affected Windows systems by sending specially crafted packets. The vulnerability is highly critical due to its wormable potential and lack of required user interaction.

Vendors: Microsoft.

Quick answers

Is CVE-2021-31166 exploited in the wild?: Yes. CVE-2021-31166 is known to be exploited in the wild, first recorded on 6 April 2022. Treat it as urgent.
How severe is CVE-2021-31166?: Critical severity, with a CVSS score of 9.8, published 6 April 2022.
Which products and versions are affected?: Microsoft Windows 10 Version 2004 up to (excluding) 10.0.19041.982; Microsoft Windows 10 Version 20H2 up to (excluding) 10.0.19042.982; Microsoft Windows Server version 2004 up to (excluding) 10.0.19041.982; Microsoft Windows Server version 20H2 up to (excluding) 10.0.19042.982.
Is there a fix for CVE-2021-31166?: A patch was published on 2021-05-11: MSRC advisory and patch released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2021-31166 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2021-31166?: Check whether you run Microsoft HTTP Protocol Stack. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

Microsoft Windows 10 Version 2004 up to (excluding) 10.0.19041.982
Microsoft Windows 10 Version 20H2 up to (excluding) 10.0.19042.982
Microsoft Windows Server version 2004 up to (excluding) 10.0.19041.982
Microsoft Windows Server version 20H2 up to (excluding) 10.0.19042.982

Timeline

2021-05-11: disclosed: NVD Published Date
2021-05-11: patched: MSRC advisory and patch released
2022-04-06: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
2022-04-06: exploited: Confirmed exploited in the wild per CISA KEV entry

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