CVE-2026-21513 — AI Deep Analysis Summary

Q: Root Cause? (CWE/Flaw)

🛡️ **Root Cause**: **CWE-693** (Protection Mechanism Failure). 🔍 **Flaw**: The MSHTML framework fails to properly enforce security restrictions, allowing unauthorized actions or data access.

Q: Who is affected? (Versions/Components)

📦 **Affected Products**: • Windows 10 Version 1607 (x64) • Windows Server 2016 (Server Core) • Windows Server 2012 • Other Windows 10 versions (truncated in data).

Q: What can hackers do? (Privileges/Data)

💻 **Attacker Capabilities**: • **Privileges**: Can bypass security features. • **Data**: High risk of data theft (C:H) and modification (I:H). • **Impact**: Full system compromise potential (A:H).

Q: Is exploitation threshold high? (Auth/Config)

⚠️ **Exploitation Threshold**: **Medium**. • **Network**: Remote (AV:N). • **Complexity**: Low (AC:L). • **User Interaction**: Required (UI:R). 👉 Victim must click/interact with malicious content.

Q: Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: **No**. • `pocs` array is empty. • No wild exploitation reported yet. • Relies on social engineering or targeted attacks.

Q: How to self-check? (Features/Scanning)

🔍 **Self-Check**: 1. Verify OS version (Win 10 1607, Server 2012/2016). 2. Check MSHTML component status. 3. Monitor for unusual HTML rendering behaviors or security policy violations.

Q: Is it urgent? (Priority Suggestion)

🔥 **Urgency**: **HIGH**. • CVSS Score: **High** (implied by C:H/I:H/A:H). • Low complexity + Remote access = Critical risk. • **Priority**: Patch immediately to prevent potential bypass attacks.

Updated May 06, 2026 CVSS 8.8 · High

This is a summary of the AI-generated 10-question deep analysis. The full version (longer answers, follow-up Q&A, related CVEs) requires login. Read the full analysis →

Q1What is this vulnerability? (Essence + Consequences)

🚨 **Essence**: A security feature bypass in Microsoft MSHTML Framework.…

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Q2Root Cause? (CWE/Flaw)

🛡️ **Root Cause**: **CWE-693** (Protection Mechanism Failure). <br>🔍 **Flaw**: The MSHTML framework fails to properly enforce security restrictions, allowing unauthorized actions or data access.

Q3Who is affected? (Versions/Components)

📦 **Affected Products**: <br>• Windows 10 Version 1607 (x64) <br>• Windows Server 2016 (Server Core) <br>• Windows Server 2012 <br>• Other Windows 10 versions (truncated in data).

Q4What can hackers do? (Privileges/Data)

💻 **Attacker Capabilities**: <br>• **Privileges**: Can bypass security features. <br>• **Data**: High risk of data theft (C:H) and modification (I:H). <br>• **Impact**: Full system compromise potential (A:H).

Q5Is exploitation threshold high? (Auth/Config)

⚠️ **Exploitation Threshold**: **Medium**. <br>• **Network**: Remote (AV:N). <br>• **Complexity**: Low (AC:L). <br>• **User Interaction**: Required (UI:R). <br>👉 Victim must click/interact with malicious content.

Q6Is there a public Exp? (PoC/Wild Exploitation)

🚫 **Public Exploit**: **No**. <br>• `pocs` array is empty. <br>• No wild exploitation reported yet. <br>• Relies on social engineering or targeted attacks.

Q7How to self-check? (Features/Scanning)

🔍 **Self-Check**: <br>1. Verify OS version (Win 10 1607, Server 2012/2016). <br>2. Check MSHTML component status. <br>3. Monitor for unusual HTML rendering behaviors or security policy violations.

Q8Is it fixed officially? (Patch/Mitigation)

✅ **Official Fix**: **Yes**. <br>• Microsoft has released an update. <br>• Reference: [MSRC Advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513).…

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Q9What if no patch? (Workaround)

🛡️ **No Patch Workaround**: <br>• Disable Internet Explorer/MSHTML if possible. <br>• Use strict Content Security Policies (CSP). <br>• Restrict user interaction with untrusted HTML content.…

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Q10Is it urgent? (Priority Suggestion)

🔥 **Urgency**: **HIGH**. <br>• CVSS Score: **High** (implied by C:H/I:H/A:H). <br>• Low complexity + Remote access = Critical risk. <br>• **Priority**: Patch immediately to prevent potential bypass attacks.

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Vulnerability detail Full AI analysis (login) Microsoft CWE-693