<p>Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.</p> <p>An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p> <p>Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”.</p> <p>Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.</p> <p>Please see the <strong>Mitigations</strong> and <strong>Workaround</strong> sections for important information about steps you can take to protect your system from this vulnerability.</p> <p><strong>UPDATE</strong> September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.</p>
総合評価: CVE-2021-40444 は在野悪用が確認された重大脅威(94.8/100)。CVSS 深刻度は高。悪用される可能性が高い(EPSS 96.84%、100 パーセンタイル) 根拠: CISA KEV に登録(追加日 2021-11-03)。Microsoft / MSHTML が対象で、弱点分類 CWE-22の悪用が確認されています。未認証でリモート管理権限を奪取されるリスクが極めて高い。 推奨対応: CISA の対応期限を過ぎています。緊急のパッチ適用を最優先に検討してください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
: Microsoft MSHTML Remote Code Execution Vulnerability · CISA KEV の詳細
: 2021-11-03
: 2021-11-17
: Apply updates per vendor instructions.
| EDB-ID | ソース | 種別 | 公開 | リンク |
|---|---|---|---|---|
| — | nvd_ref | exploit_tag | Exploit-DB ↗ | |
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置(高いほど相対的に深刻)を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ(新 − 旧) |
|---|---|---|---|---|
| 1 | 2026-06-23 | 97.24% | 96.84% | -0.40% |
| 2 | 2026-06-15 | 94.33% | 97.24% | +2.91% |
| 3 | 2026-03-23 | — | 94.33% | — |
EPSS の全履歴 (全 38 件)
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 8.8 | 3.1 | HIGH |
|
2.8 | 5.3 | [email protected] |
| 7.8 | 3.1 | HIGH |
|
1.8 | 5.9 | [email protected] |
| 6.8 | 2.0 | MEDIUM |
|
8.6 | 6.4 | [email protected] |
| ベンダー | 製品 | バージョン | 生の CPE |
|---|---|---|---|
| microsoft | windows_10_1507 | < 10.0.10240.19060 | cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:* |
| microsoft | windows_10_1607 | < 10.0.14393.4651 | cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:* |
| microsoft | windows_10_1809 | < 10.0.17763.2183 | cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:* |
| microsoft | windows_10_1909 | < 10.0.18363.1801 | cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:* |
| microsoft | windows_10_2004 | < 10.0.19041.1237 | cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:* |
| microsoft | windows_10_20h2 | < 10.0.19042.1237 | cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:* |
| microsoft | windows_10_21h1 | < 10.0.19043.1237 | cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:* |
| microsoft | windows_7 | — | cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* |
| microsoft | windows_8.1 | — | cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* |
| microsoft | windows_rt_8.1 | — | cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* |
| microsoft | windows_server_2004 | < 10.0.19041.1237 | cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:* |
| microsoft | windows_server_2008 | — | cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:* |
| microsoft | windows_server_2008 | r2 | cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* |
| microsoft | windows_server_2012 | — | cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* |
| microsoft | windows_server_2012 | — | cpe:2.3:o:microsoft:windows_server_2012:-:r2:*:*:*:*:*:* |
| microsoft | windows_server_2016 | < 10.0.14393.4651 | cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:* |
| microsoft | windows_server_2019 | < 10.0.17763.2183 | cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* |
| microsoft | windows_server_2022 | < 10.0.20348.230 | cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:* |
| microsoft | windows_server_20h2 | < 10.0.19042.1237 | cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:* |
| URL | タグ |
|---|---|
| http://packetstormsecurity.com/files/164210/Microsoft-Windows-MSHTML-Overview.html | Third Party Advisory VDB Entry |
| http://packetstormsecurity.com/files/165214/Microsoft-Office-Word-MSHTML-Remote-Code-Execution.html | Exploit Third Party Advisory VDB Entry |
| http://packetstormsecurity.com/files/167317/Microsoft-Office-MSDT-Follina-Proof-Of-Concept.html | Exploit Third Party Advisory VDB Entry |
| https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40444 | Mitigation Patch Vendor Advisory |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40444 | US Government Resource |