CVE-2025-53784 Overview
CVE-2025-53784 is a use-after-free vulnerability [CWE-416] in Microsoft Office Word that enables local code execution. The flaw affects Microsoft 365 Apps and Microsoft Office Long Term Servicing Channel (LTSC) 2021 and 2024 across Windows x86, x64, and macOS builds. An attacker can craft a malicious Word document that, when opened, triggers the use-after-free condition and executes arbitrary code in the context of the current user. Microsoft published the advisory on August 12, 2025, and the entry was last updated in the National Vulnerability Database on August 18, 2025.
Critical Impact
Successful exploitation grants the attacker code execution with the privileges of the user running Word, leading to full confidentiality, integrity, and availability impact on the targeted host.
Affected Products
- Microsoft 365 Apps (Enterprise, x86 and x64)
- Microsoft Office LTSC 2021 (x86, x64, and macOS)
- Microsoft Office LTSC 2024 (x86, x64, and macOS)
Discovery Timeline
- 2025-08-12 - CVE-2025-53784 published to NVD and Microsoft Security Response Center advisory released
- 2025-08-18 - Last updated in NVD database
Technical Details for CVE-2025-53784
Vulnerability Analysis
The vulnerability is a use-after-free condition [CWE-416] within Microsoft Office Word's document parsing logic. Use-after-free flaws occur when a program continues to reference memory after it has been released back to the allocator. An attacker who controls the contents and structure of a Word document can manipulate object lifetimes so that a freed object is reused during subsequent processing. The reused allocation can be replaced with attacker-controlled data, allowing the freed object's virtual function pointers or callback fields to redirect execution. This results in arbitrary code execution in the context of the user opening the document.
Root Cause
The root cause is improper tracking of object lifetimes in Word's handling of complex document structures. A pointer continues to reference memory after the underlying object has been freed, and that pointer is later dereferenced during normal document processing. The condition does not require authentication or user interaction beyond opening a crafted file.
Attack Vector
The attack vector is local, meaning the malicious document must be processed on the target machine. Delivery typically occurs through phishing email attachments, malicious file shares, or web downloads. Because Office's Preview Pane can render document content, exploitation may succeed without an explicit "open" action by the user. No privileges are required on the host, and exploitation does not require user interaction beyond standard document handling.
No public proof-of-concept exploit code is available for CVE-2025-53784 at the time of writing. Refer to the Microsoft Security Advisory for vendor technical details.
Detection Methods for CVE-2025-53784
Indicators of Compromise
- Word processes (WINWORD.EXE) spawning unexpected child processes such as cmd.exe, powershell.exe, wscript.exe, or rundll32.exe.
- Word writing executable files, DLLs, or scripts to %TEMP%, %APPDATA%, or user profile directories shortly after a document is opened.
- Unexpected outbound network connections initiated by WINWORD.EXE to previously unseen domains or IP addresses.
- Crash reports or Windows Error Reporting events referencing access violations in Word modules following the opening of a .docx, .doc, or .rtf file.
Detection Strategies
- Hunt for process-tree anomalies where Office applications spawn scripting interpreters or living-off-the-land binaries (LOLBins).
- Inspect documents arriving from external email senders for unusual embedded objects, malformed structures, or oversized OLE streams.
- Correlate Word crashes with subsequent suspicious activity on the same endpoint within a short time window.
Monitoring Recommendations
- Enable command-line and process-creation logging (Windows Event ID 4688 with command-line auditing, or Sysmon Event ID 1).
- Forward Office telemetry and endpoint process events to a centralized analytics platform for retrospective hunting.
- Monitor for the deployment of the August 2025 Office security updates across the fleet to identify unpatched endpoints.
How to Mitigate CVE-2025-53784
Immediate Actions Required
- Apply the Microsoft August 2025 security updates for Microsoft 365 Apps and Office LTSC 2021/2024 on all Windows and macOS endpoints.
- Prioritize patching for users who routinely process external Word documents, including finance, HR, executive assistants, and customer-facing roles.
- Block or quarantine inbound Word attachments from untrusted senders at the email gateway until patching is verified.
- Enable Office Protected View and Application Guard for documents originating from the internet or other untrusted locations.
Patch Information
Microsoft released fixes through the standard Office update channels. Consult the Microsoft Security Advisory for the specific build numbers corresponding to Microsoft 365 Apps, Office LTSC 2021, and Office LTSC 2024 on each supported architecture. Click-to-Run installations update through the Office update service; LTSC and macOS builds use their respective update mechanisms.
Workarounds
- Disable the Outlook and File Explorer Preview Pane to prevent automatic rendering of untrusted documents.
- Enforce Office macro restrictions and block macros in files originating from the internet via Group Policy.
- Configure Attack Surface Reduction (ASR) rules to block Office applications from creating child processes and from injecting code into other processes.
# Example: enable ASR rule to block Office child process creation (PowerShell)
Set-MpPreference -AttackSurfaceReductionRules_Ids D4F940AB-401B-4EFC-AADC-AD5F3C50688A `
-AttackSurfaceReductionRules_Actions Enabled
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
