CVE-2025-47162: Microsoft 365 Apps Buffer Overflow Flaw

CVE-2025-47162 Overview

CVE-2025-47162 is a heap-based buffer overflow vulnerability in Microsoft Office that allows an unauthorized attacker to execute code locally. The flaw affects multiple Microsoft Office releases, including Microsoft 365 Apps, Office 2016, Office 2019, and Office Long Term Servicing Channel 2021 and 2024 on both Windows and macOS. The vulnerability maps to [CWE-122] and resides in Office's handling of crafted document content. Microsoft published the advisory on June 10, 2025.

Critical Impact

A successful exploit yields arbitrary code execution in the context of the user opening a malicious Office document, enabling full compromise of confidentiality, integrity, and availability.

Affected Products

• Microsoft 365 Apps (Enterprise)
• Microsoft Office 2016, Office 2019, and Office for Android
• Microsoft Office Long Term Servicing Channel 2021 and 2024 (Windows and macOS)

Discovery Timeline

• 2025-06-10 - CVE-2025-47162 published to NVD and Microsoft Security Response Center advisory released
• 2025-07-09 - Last updated in NVD database

Technical Details for CVE-2025-47162

Vulnerability Analysis

The vulnerability is a heap-based buffer overflow ([CWE-122]) in Microsoft Office. Attackers craft a malicious Office document that triggers improper bounds handling during parsing. When Office processes the malformed structure, it writes data past the bounds of a heap-allocated buffer. The corrupted heap memory enables an attacker to redirect control flow and execute arbitrary code in the context of the current user. Successful exploitation does not require authentication or user interaction beyond opening the document through normal Office workflows. Because the affected products span Windows, macOS, and Android editions of Office, the attack surface covers most enterprise productivity environments.

Root Cause

The root cause is insufficient validation of length or size fields during deserialization of structured Office document data. The parser allocates a heap buffer based on one value, then copies a larger payload controlled by attacker-supplied content. This out-of-bounds heap write corrupts adjacent allocations, including object headers and function pointers used during later document rendering.

Attack Vector

The attack vector is local. An attacker delivers a weaponized Office file through phishing email, malicious file shares, removable media, or drive-by download. When a user opens the document, the parsing routine triggers the overflow without further interaction. Office's Protected View may reduce risk for files originating from the internet, but documents delivered through trusted channels bypass that mitigation.

No verified public exploit code is available. See the Microsoft CVE-2025-47162 Advisory for vendor technical details.

Detection Methods for CVE-2025-47162

Indicators of Compromise

• Office processes (WINWORD.EXE, EXCEL.EXE, POWERPNT.EXE) spawning unexpected child processes such as cmd.exe, powershell.exe, wscript.exe, or rundll32.exe.
• Office applications writing executable content (.exe, .dll, .hta, .js) to user-writable directories such as %TEMP%, %APPDATA%, or %LOCALAPPDATA%.
• Crash events for Office binaries with heap corruption signatures in Windows Error Reporting (WerFault.exe).
• Inbound documents from external senders containing unusual embedded objects or non-standard structured storage streams.

Detection Strategies

• Hunt for parent-child process relationships where Office binaries launch interpreters or LOLBins, correlated with recent document opens.
• Apply YARA rules targeting malformed Office binary structures associated with heap-overflow proof-of-concepts as they emerge.
• Inspect email gateway and proxy logs for Office attachments with anomalous size, macro indicators, or origins from low-reputation domains.

Monitoring Recommendations

• Enable Microsoft Defender Attack Surface Reduction rules that block Office from creating child processes and writing executable content.
• Forward Sysmon Event IDs 1, 7, and 11 from endpoints running Office to a centralized SIEM for behavioral correlation.
• Track Office application crashes through Application event log entries (Event IDs 1000, 1001) for unexplained spikes that may indicate exploit testing.

How to Mitigate CVE-2025-47162

Immediate Actions Required

• Apply the June 2025 Microsoft security updates to all affected Office installations, prioritizing internet-exposed and high-privilege users.
• Verify update deployment across Microsoft 365 Apps, Office 2016, Office 2019, and Office LTSC 2021 and 2024 on both Windows and macOS endpoints.
• Re-enable and enforce Protected View and Office Hardened Runtime settings through Group Policy or Intune.
• Restrict opening of Office documents originating from external email and untrusted file shares.

Patch Information

Microsoft released fixes through standard update channels on June 10, 2025. Refer to the Microsoft CVE-2025-47162 Advisory for the specific build numbers and KB articles for each affected product channel. Microsoft 365 Apps customers receive updates through Click-to-Run; volume-licensed Office and Office LTSC require deployment of the corresponding MSI or update package.

Workarounds

• Configure Office to block documents from the internet by enforcing Protected View for files from Outlook attachments, the internet, and unsafe locations.
• Disable rich content rendering (ActiveX, embedded objects, legacy file formats) for users who do not require it through Trust Center policies.
• Use Microsoft Defender Attack Surface Reduction rules to block child process creation and Win32 API calls from Office macros.

# Example: enforce ASR rules via PowerShell to reduce Office exploit impact
Set-MpPreference -AttackSurfaceReductionRules_Ids `
  D4F940AB-401B-4EFC-AADC-AD5F3C50688A `
  -AttackSurfaceReductionRules_Actions Enabled

Set-MpPreference -AttackSurfaceReductionRules_Ids `
  3B576869-A4EC-4529-8536-B80A7769E899 `
  -AttackSurfaceReductionRules_Actions Enabled