CVE-2025-24082: Microsoft 365 Apps Use After Free Flaw

CVE-2025-24082 Overview

CVE-2025-24082 is a use-after-free vulnerability [CWE-416] in Microsoft Office Excel that enables local code execution. An attacker can exploit the flaw by convincing a user to open a crafted Excel file. Successful exploitation runs attacker-controlled code in the context of the current user, compromising confidentiality, integrity, and availability.

The vulnerability affects multiple Microsoft Office editions across Windows and macOS, including Microsoft 365 Apps, Excel 2016, Office 2019, the Office Long Term Servicing Channel (LTSC) 2021 and 2024, and Office Online Server. Microsoft published the advisory on March 11, 2025 as part of its monthly security update cycle.

Critical Impact
Successful exploitation grants arbitrary code execution under the logged-in user's identity, providing a foothold for further compromise through phishing-delivered Excel documents.

Affected Products

Microsoft 365 Apps for Enterprise (x64 and x86)
Microsoft Excel 2016, Microsoft Office 2019, and Office LTSC 2021/2024 (Windows and macOS)
Microsoft Office Online Server

Discovery Timeline

2025-03-11 - CVE-2025-24082 published to the National Vulnerability Database
2025-03-11 - Microsoft released a security patch through the March 2025 update cycle
2025-07-02 - Last updated in the NVD database

Technical Details for CVE-2025-24082

Vulnerability Analysis

The vulnerability is a use-after-free condition [CWE-416] inside Microsoft Office Excel. Use-after-free flaws occur when a program continues to reference memory after it has been released, allowing attackers to manipulate the freed allocation before reuse. In Excel, parsing of a malformed document triggers premature object release while later code paths still operate on the dangling pointer.

Exploitation requires user interaction. The victim must open a malicious workbook delivered through email, instant messaging, or a web download. Attack complexity is low and no privileges are required beyond convincing the user to open the file.

Root Cause

The root cause is improper object lifetime management within Excel's document parsing routines. When the application processes a specially crafted file, an internal object is freed while a reference to the same allocation remains active. Subsequent operations on that reference allow an attacker to redirect program execution by spraying the freed slot with controlled data.

Attack Vector

The attack vector is local and requires social engineering. An attacker crafts a malicious .xlsx, .xls, or related Excel format file and delivers it to the target. Once opened, Excel processes the embedded structures and triggers the use-after-free, leading to arbitrary code execution as the current user. Code executed at user scope enables credential theft, data exfiltration, or staging of additional payloads such as ransomware loaders.

No public proof-of-concept exploit and no entry on the CISA Known Exploited Vulnerabilities catalog are recorded for this CVE at the time of writing. Full technical details are restricted to the Microsoft CVE-2025-24082 Advisory.

Detection Methods for CVE-2025-24082

Indicators of Compromise

Excel processes (excel.exe) spawning unexpected child processes such as cmd.exe, powershell.exe, rundll32.exe, or mshta.exe.
Excel crashes followed by anomalous network connections or new persistence entries under HKCU\Software\Microsoft\Windows\CurrentVersion\Run.
Unsigned or unusual DLLs loaded into the Office process address space shortly after document open events.
Inbound Excel attachments from external senders containing macros, embedded objects, or oversized record streams.

Detection Strategies

Hunt for parent-child process relationships where Office applications launch interpreters or living-off-the-land binaries.
Inspect Office telemetry and Windows Event Logs for repeated Excel application crashes correlated with recently received email attachments.
Apply YARA or static rules that flag malformed Excel records and embedded shellcode patterns at the email gateway.

Monitoring Recommendations

Enable Microsoft Defender Attack Surface Reduction rules that block Office applications from creating child processes and injecting code into other processes.
Forward endpoint, email gateway, and Office 365 audit logs into a centralized SIEM with behavioral correlation across user, host, and document identifiers.
Track patch compliance for Office builds across the fleet and alert when out-of-date versions open documents from external sources.

How to Mitigate CVE-2025-24082

Immediate Actions Required

Deploy the March 2025 Microsoft Office security updates referenced in the Microsoft CVE-2025-24082 Advisory to all affected endpoints and servers.
Prioritize patching for users who routinely process external spreadsheets, including finance, procurement, and executive assistant roles.
Verify that Microsoft 365 Apps update channels are not paused and that Office LTSC installations have received the corresponding cumulative update.

Patch Information

Microsoft released fixes for CVE-2025-24082 on March 11, 2025. Updates are available through Microsoft Update, the Microsoft Update Catalog, and the click-to-run channel for Microsoft 365 Apps. Office Online Server requires the dedicated server-side update package. Apply updates to Excel 2016, Office 2019, Office LTSC 2021, and Office LTSC 2024 on both Windows and macOS where applicable.

Workarounds

Enable Protected View and Office Application Guard so untrusted documents open in an isolated container.
Block or quarantine inbound Excel files from external senders at the email gateway until patches are confirmed deployed.
Disable execution of macros and embedded content by policy for users who do not require these features.
Train users to validate the origin of spreadsheet attachments before opening, especially unsolicited financial or invoice files.

bash

# Example Group Policy registry settings to enforce Protected View for Excel
reg add "HKCU\Software\Policies\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableAttachmentsInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Policies\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Policies\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableUnsafeLocationsInPV /t REG_DWORD /d 0 /f

# Block Office apps from creating child processes via Defender ASR
Set-MpPreference -AttackSurfaceReductionRules_Ids D4F940AB-401B-4EFC-AADC-AD5F3C50688A -AttackSurfaceReductionRules_Actions Enabled