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📍 Report Snapshot

[!IMPORTANT] This report is intentionally sanitized for public GitHub publication. Sensitive identifiers, credentials, infrastructure values, and client-specific evidence are replaced with clear placeholders.

🧭 Quick Navigation

• Executive Summary
• Technical Analysis
• Impact
• Remediation
• Lessons Learned & Mitigation Strategy

[!TIP] For a fast review, start with the Executive Summary and Impact sections. For technical depth, continue into Technical Analysis and Remediation.

🏷️ Title

CVE-2026-45659 - Microsoft SharePoint Deserialization RCE

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🧾 Executive Summary

ثغرة أمنية في Microsoft SharePoint Server 2019/2022 و Subscription Edition تسمح لمستخدم مُصادق بصلاحيات منخفضة (Site Member) بتنفيذ أوامر عشوائية على الخادم (RCE). تستغل الثغرة آلية إلغاء التسلسل غير الآمنة (Unsafe Deserialization) في معالج LosFormatter.Deserialize داخل مكتبة Microsoft.SharePoint.Library.

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🔬 Technical Analysis

The weakness was assessed from an application-security and infrastructure-risk perspective. The core issue is classified as Remote Code Execution and was documented in a sanitized form suitable for public portfolio publication.

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📊 Impact

• Unauthorized command execution within the affected application context.
• Potential service takeover, data exposure, and lateral movement depending on deployment privileges.

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🛠️ Remediation

1. تطبيق تحديث مايو 2026 من Microsoft
2. تقييد صلاحيات المستخدمين إلى الحد الأدنى
3. مراقبة استدعاءات SPListItem.Update() غير الطبيعية
4. تفعيل Advanced Threat Protection في SharePoint

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🧠 Lessons Learned & Mitigation Strategy

• Treat every integration boundary as untrusted, especially when application logic forwards user-controlled values to filesystems, shells, parsers, or external tools.
• Security reviews should validate the complete exploit chain, not only the first vulnerable endpoint; low-severity misconfigurations can become critical when chained.
• Public-facing documentation should describe risk, root cause, and remediation without exposing operational identifiers, credentials, or reusable exploitation artifacts.
• Defensive controls should combine preventive validation, runtime least privilege, telemetry, and patch governance to reduce both exploitability and blast radius.

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🧼 Publication Sanitization Notes

• Sensitive infrastructure identifiers, IP addresses, hostnames, credentials, hashes, and e-mail addresses were replaced with explicit placeholders.
• Reusable operational evidence was minimized or abstracted to keep the document suitable for public GitHub publication.
• The document uses a consultant-style structure aligned with common web security testing report practices such as OWASP WSTG reporting expectations.

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