ntlm leakage

About this tag
NTLM leakage refers to the unintended disclosure of Windows NTLM authentication hashes, often triggered when a client or server connects to an attacker-controlled SMB or UNC path. On WindowsForum.com, discussions cover vulnerabilities such as CVE-2026-20872 in File Explorer, CVE-2025-59775 in Apache HTTP Server on Windows, and related attack vectors involving preview handlers and SSRF. Mitigations include disabling the File Explorer preview pane for internet-downloaded files, patching to Apache httpd 2.4.66, and applying Microsoft's October 2025 security updates. These threads provide practical guidance for administrators and security professionals to reduce exposure to NTLM relay and offline cracking attacks.

  1. CVE-2026-20872 NTLM Leak in File Explorer: Mitigations and Guidance

    Microsoft’s security channels have logged CVE-2026-20872 as an NTLM hash disclosure / spoofing vulnerability tied to File Explorer and preview/metadata handling — a class of bug that repeatedly enables low‑interaction credential leakage by coaxing Windows clients to authenticate to...
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    • cve 2026 20872 file explorer security ntlm leakage windows defense
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    • Forum: Security Alerts

  2. Apache Windows SSRF CVE-2025-59775: Patch to 2.4.66 to Stop NTLM Leakage

    Apache HTTP Server has a Windows-only Server-Side Request Forgery (SSRF) flaw that can be forced to make the server connect to attacker-controlled UNC (SMB) targets and thereby leak NTLM authentication material — a vulnerability tracked as CVE-2025-59775 and fixed in Apache httpd 2.4.66...
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    • apache httpd ntlm leakage ssrf vulnerability windows security
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    • Forum: Security Alerts

  3. Explorer Preview Disabled for Internet Files to Stop NTLM Leaks

    The File Explorer preview pane in Windows has been deliberately neutered for internet-downloaded files after security researchers and Microsoft found a practical way for preview handlers to coax NTLM authentication material out of a running system — a low‑interaction path that could leak NTLM...
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    • file explorer ntlm leakage preview pane security updates
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    • Forum: Windows News

  4. Windows Explorer Preview Pane Disabled for Internet Files in October 2025 Update

    Microsoft has turned off File Explorer’s Preview pane for files tagged as coming from the internet, a deliberate security hardening shipped in the October 2025 security rollup that trades a decades‑old convenience for protection against a subtle but real credential‑leak attack vector. Background...
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    • file explorer mark of the web ntlm leakage windows security
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    • Forum: Windows News

  5. CVE-2025-52488: Unicode Normalization Bypass in DotNetNuke Threatens Windows Security

    A critical vulnerability in DotNetNuke (DNN), catalogued as CVE-2025-52488, has placed the spotlight on the complex interplay of Windows file system operations, .NET behavior, and subtle Unicode normalization pitfalls. Although DNN is recognized for its robust enterprise-ready architecture and...
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    • .net security credential theft cve-2025-52488 cybersecurity cybersecurity vulnerabilities dotnetnuke file path file security file system normalization ntlm leakage ntlm relay pre-authentication smb vulnerability unc path unicode normalization unicode security risks web application risks windows cms security windows security
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    • Forum: Windows News