CVE-2025-47174 Overview
CVE-2025-47174 is a heap-based buffer overflow vulnerability in Microsoft Office Excel that enables local code execution. The flaw, classified under [CWE-122], allows an unauthorized attacker to execute arbitrary code in the context of the current user when a victim opens a crafted Excel file. Microsoft published the advisory on June 10, 2025, and the issue affects current Microsoft 365 Apps and Office Long-Term Servicing Channel (LTSC) builds. Exploitation requires user interaction, typically through a phishing email or malicious download containing a weaponized spreadsheet.
Critical Impact
Successful exploitation allows arbitrary code execution with the privileges of the logged-on user, enabling data theft, persistence, and lateral movement from a single opened Excel document.
Affected Products
- Microsoft 365 Apps - Enterprise edition
- Microsoft Office Long-Term Servicing Channel 2021
- Microsoft Office Long-Term Servicing Channel 2024
Discovery Timeline
- 2025-06-10 - CVE-2025-47174 published to NVD with Microsoft advisory
- 2025-07-09 - Last updated in NVD database
Technical Details for CVE-2025-47174
Vulnerability Analysis
The vulnerability is a heap-based buffer overflow ([CWE-122]) inside the Microsoft Office Excel parsing routines. When Excel processes a malformed spreadsheet structure, it writes data past the bounds of an allocated heap buffer. The overflow corrupts adjacent heap metadata or function pointers, allowing attackers to redirect execution flow. Because Excel runs with the privileges of the logged-on user, code executes in that user context, granting full access to user files, network shares, and stored credentials. The attack vector is local and requires the victim to open a crafted file, but no authentication on the target system is needed.
Root Cause
The root cause is improper validation of length or size values when Excel allocates and populates heap buffers for embedded objects or record structures. The parser trusts attacker-controlled fields in the file format, leading to an undersized allocation followed by an oversized copy operation. Microsoft has not published low-level technical details beyond the Microsoft CVE-2025-47174 Advisory.
Attack Vector
An attacker crafts a malicious .xlsx, .xls, or related Office document and delivers it via email, instant message, or web download. The victim must open the file in a vulnerable Excel build. Preview Pane interactions can also serve as an attack surface for Office file format vulnerabilities. No network access or elevated privileges on the target system are required for the initial compromise.
No public proof-of-concept or in-the-wild exploitation has been confirmed for CVE-2025-47174 at the time of publication. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2025-47174
Indicators of Compromise
- Excel process (EXCEL.EXE) spawning unusual child processes such as cmd.exe, powershell.exe, rundll32.exe, or wscript.exe
- Unexpected outbound network connections originating from EXCEL.EXE shortly after document open
- Crash dumps or Windows Error Reporting (WER) events referencing heap corruption in Excel modules
- Office documents written to disk from email clients or browsers followed immediately by suspicious process creation
Detection Strategies
- Hunt for parent-child process relationships where EXCEL.EXE launches script interpreters, LOLBins, or unsigned binaries
- Inspect inbound email attachments and web downloads for Excel files containing anomalous OLE streams or malformed records
- Correlate Office telemetry with endpoint logs to identify document opens that immediately precede credential access or persistence behaviors
Monitoring Recommendations
- Enable Microsoft Defender Attack Surface Reduction (ASR) rules that block Office applications from creating child processes and from injecting code into other processes
- Forward Sysmon process creation, image load, and network connection events to a centralized analytics platform for correlation
- Monitor Windows Error Reporting and application crash events for repeated faults in Excel that may indicate exploitation attempts or unstable exploit chains
How to Mitigate CVE-2025-47174
Immediate Actions Required
- Apply the June 2025 Microsoft security updates for Microsoft 365 Apps and Office LTSC 2021 and 2024 builds without delay
- Inventory endpoints to confirm Office update channels are receiving and installing the patched builds
- Enforce Protected View and Block Macros from the Internet via Group Policy to reduce exposure from email-borne documents
- Train users to avoid opening unsolicited spreadsheets and to report suspicious attachments
Patch Information
Microsoft has released security updates addressing CVE-2025-47174. Administrators should reference the Microsoft CVE-2025-47174 Advisory for the current list of fixed builds across Microsoft 365 Apps, Office LTSC 2021, and Office LTSC 2024. Update through standard channels including Microsoft Update, Office Click-to-Run, WSUS, or Microsoft Intune.
Workarounds
- Disable the Preview Pane in Outlook and Windows Explorer to prevent automatic parsing of Office attachments
- Configure Microsoft Defender ASR rule D4F940AB-401B-4EFC-AADC-AD5F3C50688A to block Office applications from creating child processes
- Restrict opening of Office documents originating from the internet by enforcing Mark-of-the-Web and Protected View policies
- Deploy application allowlisting to prevent unauthorized binaries spawned by Excel from executing
# Configuration example: enforce ASR rule blocking Office child processes via PowerShell
Set-MpPreference -AttackSurfaceReductionRules_Ids D4F940AB-401B-4EFC-AADC-AD5F3C50688A `
-AttackSurfaceReductionRules_Actions Enabled
# Verify the rule is enabled
Get-MpPreference | Select-Object -ExpandProperty AttackSurfaceReductionRules_Ids
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
