CVE-2026-5242 Overview
CVE-2026-5242 is a CSV formula injection vulnerability in MIA Technology Inc. Pizzy Library. The library fails to neutralize formula elements when generating CSV files, enabling Code Injection [CWE-1236]. An authenticated attacker with low privileges can supply crafted input that becomes an active spreadsheet formula when the resulting CSV file is opened in applications such as Microsoft Excel or LibreOffice Calc. Successful exploitation allows execution of attacker-controlled formulas on the victim system, leading to potential command execution, data exfiltration, and full compromise of confidentiality, integrity, and availability. The vulnerability affects Pizzy Library versions 1.0.0.26250 through 1.3.9.26250 (exclusive).
Critical Impact
Authenticated attackers can inject spreadsheet formulas into generated CSV files, leading to code execution on victim workstations when the file is opened.
Affected Products
- MIA Technology Inc. Pizzy Library 1.0.0.26250
- MIA Technology Inc. Pizzy Library versions through 1.3.8.26250
- All deployments using Pizzy Library prior to 1.3.9.26250
Discovery Timeline
- 2026-06-15 - CVE-2026-5242 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-5242
Vulnerability Analysis
The vulnerability resides in the CSV generation logic of the Pizzy Library. The library does not sanitize user-supplied data before writing it to CSV output. When a field begins with characters such as =, +, -, @, tab, or carriage return, spreadsheet applications interpret the value as a formula rather than literal text. This class of issue is tracked under [CWE-1236: Improper Neutralization of Formula Elements in a CSV File].
An attacker submits content through any input channel that the application later exports through Pizzy Library. The malicious payload remains dormant inside the CSV file. Execution occurs when an end user opens the file in a spreadsheet application that evaluates formulas automatically. Formulas can invoke functions such as DDE, HYPERLINK, or WEBSERVICE to execute commands, leak data to attacker-controlled endpoints, or redirect users to phishing sites.
Root Cause
The library writes input values to CSV cells without prefixing dangerous leading characters or quoting fields that begin with formula triggers. The exported file inherits the trust context of the application that generated it, increasing the likelihood that recipients open it without inspection.
Attack Vector
The attack vector is network-based and requires low privileges. An authenticated user injects a payload such as =cmd|'/C calc'!A1 into a form, record, or data field. When an administrator or another user exports the data to CSV using Pizzy Library and opens the file, the formula executes within the spreadsheet application. No code example is published for this advisory; see the Siber Güvenlik Notification TR-26-0383 for additional details.
Detection Methods for CVE-2026-5242
Indicators of Compromise
- CSV files generated by Pizzy Library containing cells that start with =, +, -, or @ followed by spreadsheet function names
- Outbound DNS or HTTP requests originating from EXCEL.EXE or soffice.bin shortly after a user opens an exported CSV
- Child processes spawned by spreadsheet applications, including cmd.exe, powershell.exe, or mshta.exe
Detection Strategies
- Inspect exported CSV artifacts for fields beginning with formula trigger characters before distribution
- Hunt endpoint telemetry for spreadsheet processes launching command interpreters or scripting engines
- Correlate user-supplied input in application logs with the contents of subsequently exported CSV files
Monitoring Recommendations
- Alert on EXCEL.EXE or soffice.bin initiating network connections to unrecognized domains
- Log all CSV export operations performed through Pizzy Library and retain samples for review
- Monitor application input fields for spreadsheet formula prefixes and flag anomalous submissions
How to Mitigate CVE-2026-5242
Immediate Actions Required
- Upgrade Pizzy Library to version 1.3.9.26250 or later across all applications that depend on it
- Audit existing CSV exports for embedded formula payloads and quarantine suspicious files
- Restrict export functionality to trusted user roles until patching is complete
Patch Information
MIA Technology Inc. addressed CVE-2026-5242 in Pizzy Library version 1.3.9.26250. Consult the Siber Güvenlik Notification TR-26-0383 for vendor-provided remediation details.
Workarounds
- Sanitize user input by prefixing values starting with =, +, -, @, tab, or carriage return with a single quote before CSV export
- Wrap all CSV field values in double quotes and escape internal quotes per RFC 4180
- Configure spreadsheet applications via Group Policy to disable automatic formula execution and Dynamic Data Exchange (DDE)
# Configuration example - disable DDE in Microsoft Excel via registry
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security" /v WorkbookLinkWarnings /t REG_DWORD /d 2 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security" /v DisableDDEServerLaunch /t REG_DWORD /d 1 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Excel\Security" /v DisableDDEServerLookup /t REG_DWORD /d 1 /f
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
