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CVE-2025-27727 is a local elevation-of-privilege vulnerability in Microsoft Windows Installer (msiexec.exe / msi.dll). The flaw is described by Microsoft as improper link resolution before file access ('link following'), but the provided technical context shows a logic issue in the COM-exposed transaction handling path. A low-privileged user can invoke the Windows Installer COM interface, create an MSI transaction via MsiBeginTransactionW(), and then call SetEEUIDirectoryAndFilter() with an attacker-controlled directory path. That method checks only whether the caller has DELETE permission on the directory and does not verify that the directory was created or owned by Windows Installer. The path is then written into HKLM\Software\Microsoft\Windows\CurrentVersion\Installer\TempPackages via ScheduleFileOrFolderDelete(). Later, CleanupTempPackages() / CleanupTempPackagesInternal() processes those registry entries under SYSTEM privileges, trusts the stored path, and calls FDeleteFolder() to recursively delete the attacker-selected folder and its contents. The write-up further describes exploitation by targeting C:\Config.Msi, deleting and recreating it with permissive ACLs, and then abusing Windows Installer rollback-script handling to replace a legitimate .rbs rollback script with a malicious one that executes as SYSTEM.
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A logic vulnerability in the Microsoft Windows Installer COM interface (msi.dll / msiexec.exe) that lets a low-privileged user schedule an arbitrary folder for deletion by the SYSTEM-level MSI service, enabling privilege escalation to SYSTEM.
Windows Installer elevation of privilege vulnerability that Microsoft assesses as more likely to be exploited within 30 days.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.