CVE-2022-22716: Microsoft Excel Information Disclosure

CVE-2022-22716 Overview

CVE-2022-22716 is an information disclosure vulnerability affecting Microsoft Excel and related Microsoft Office products. The flaw allows an attacker to read sensitive memory contents from an Excel process when a user opens a crafted spreadsheet file. The vulnerability is classified under [CWE-119] as an improper restriction of operations within the bounds of a memory buffer. Exploitation requires local access and user interaction, but no special privileges. Microsoft released a security update in February 2022 to address the issue across Microsoft 365 Apps, Excel 2013/2016, Office 2019, Office LTSC 2021, Office Online Server, Office Web Apps, and SharePoint Server 2013.

Critical Impact

Successful exploitation discloses confidential memory contents from the Excel process, which can expose document data, credentials, or other sensitive information loaded in memory.

Affected Products

• Microsoft 365 Apps (Enterprise, x64 and x86)
• Microsoft Excel 2013 SP1 and Excel 2016
• Microsoft Office 2019 (Windows and macOS), Office LTSC 2021, Office Online Server, Office Web Apps 2013 SP1, and SharePoint Server 2013 SP1

Discovery Timeline

• 2022-02-09 - CVE-2022-22716 published to NVD and Microsoft releases security patch
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-22716

Vulnerability Analysis

CVE-2022-22716 is an information disclosure vulnerability in the Microsoft Excel file parsing logic. The defect is tracked under [CWE-119], indicating a memory buffer boundary issue. When Excel processes a maliciously crafted spreadsheet, the parser reads beyond the intended buffer boundaries and returns memory contents that should remain inaccessible to the document context. The disclosed bytes can include process heap data such as fragments of other open documents, authentication tokens, or pointers useful for bypassing Address Space Layout Randomization (ASLR).

The attack requires the victim to open the crafted file on a local Excel installation. No elevated privileges are needed, and the vulnerability does not affect file integrity or availability. The EPSS data indicates a probability of approximately 3.76% with a percentile of 88.16, reflecting elevated relative exploitation likelihood among scored CVEs even though no public exploit is confirmed.

Root Cause

The root cause is improper validation of structure sizes or offsets during parsing of Excel document content. The parser trusts attacker-controlled length or index fields, allowing an out-of-bounds read against an internal buffer. Microsoft has not published technical internals beyond the advisory entry.

Attack Vector

An attacker delivers a crafted spreadsheet through email, web download, file share, or SharePoint upload. When the user opens the document in a vulnerable Excel client or renders it via Office Online Server or Office Web Apps, the parser triggers the out-of-bounds read. The attacker must combine the read primitive with a separate channel, such as embedded formulas, OLE objects, or external data connections, to exfiltrate the leaked bytes.

No verified proof-of-concept code is publicly available. Refer to the Microsoft Security Update CVE-2022-22716 advisory for vendor details.

Detection Methods for CVE-2022-22716

Indicators of Compromise

• Excel process (EXCEL.EXE) opening spreadsheet files from untrusted email attachments or browser downloads, followed by outbound network connections to unfamiliar hosts.
• Office applications spawning unexpected child processes, such as cmd.exe, powershell.exe, or wscript.exe, immediately after a document is opened.
• Crash dumps or Windows Error Reporting events tied to EXCEL.EXE shortly after a user opens a new document.

Detection Strategies

• Hunt for Excel documents containing external data connections, suspicious OLE objects, or unusual binary record streams using static file analysis tooling.
• Correlate Microsoft Defender SmartScreen and Mark-of-the-Web telemetry with subsequent Office process activity to identify risky document opens.
• Apply MITRE ATT&CK mapping for T1203 (Exploitation for Client Execution) and T1566.001 (Spearphishing Attachment) to focus identification logic on Office-borne payloads.

Monitoring Recommendations

• Forward Office telemetry, Sysmon process and file events, and email gateway logs to a centralized analytics platform for correlation.
• Alert on Excel reading or writing to AppData, Temp, or user profile paths shortly after launch from an Outlook or browser context.
• Track patch compliance across Microsoft 365 Apps, Office 2019, Office LTSC 2021, and SharePoint Server 2013 using endpoint configuration management data.

How to Mitigate CVE-2022-22716

Immediate Actions Required

• Apply the February 2022 Microsoft security update for every affected Office product as identified in the Microsoft Security Update CVE-2022-22716 advisory.
• Inventory endpoints and servers running Excel 2013 SP1, Excel 2016, Office 2019, Office LTSC 2021, Microsoft 365 Apps, Office Online Server, Office Web Apps 2013 SP1, and SharePoint Server 2013 SP1.
• Confirm that Microsoft 365 Apps clients are on a supported update channel and have received the patched build.

Patch Information

Microsoft published patches for all affected products on 2022-02-09. Administrators should deploy the corresponding February 2022 cumulative updates via Microsoft Update, WSUS, Microsoft Intune, or Configuration Manager. For SharePoint Server 2013 SP1 and Office Online Server, apply the server-side updates listed in the advisory and restart the affected services after installation.

Workarounds

• Enable Protected View and Office Application Guard so untrusted documents open in an isolated container that limits memory access.
• Block macros and external content in files originating from the internet using the Office Cloud Policy Service or Group Policy.
• Use email gateway controls to strip or quarantine Excel attachments from untrusted senders until patching is complete.

# Group Policy registry settings to enforce Protected View and block internet-sourced macros for Excel
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security\ProtectedView" /v DisableAttachmentsInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security" /v BlockContentExecutionFromInternet /t REG_DWORD /d 1 /f