CVE-2026-73195 in Syncope
Summary
by MITRE • 09/14/2026
Improper Encoding or Escaping of Output vulnerability in Apache Syncope.
Authenticated users can store a spreadsheet formula payload in one of their own plain attributes. When such users are included in a CSV export and the generated CSV file is opened by a spreadsheet application, the formula may be executed.
This issue affects Apache Syncope: from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 Through 4.0.7, from 4.1.0-M0 through 4.1.2.
Users are recommended to upgrade to version 4.0.8 / 4.1.3, which fix this issue.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in Apache Syncope represents a classic instance of improper encoding or escaping of output, specifically manifesting as an Insecure Export functionality that leads to Server-Side Request Forgery-like effects through client-side code execution. This flaw allows authenticated users to inject malicious spreadsheet formulas into plain text attributes within their user profiles. When these compromised records are subsequently exported via the application's CSV generation feature, the raw formula payload is written directly into the output file without adequate sanitization or escaping mechanisms. The severity of this issue stems from the behavior of modern spreadsheet applications such as Microsoft Excel, LibreOffice Calc, or Google Sheets, which automatically parse and execute formulas contained within cells upon opening the document. This creates a direct pathway for arbitrary code execution on the victim's local machine under specific conditions.
From a technical perspective, the root cause lies in the failure to distinguish between data intended for display and commands intended for interpretation by downstream applications. While CSV files are generally treated as plain text, spreadsheet parsers interpret content starting with equals signs or other formula delimiters as executable instructions rather than static strings. By storing a payload such as =cmd|/C calc!A1 in an attribute that is later exported to CSV, the attacker leverages this parsing behavior. The vulnerability affects multiple versions of Apache Syncope, including releases from 3.0.0-M0 through 3.0.16 and 4.0.0-M0 through 4.0.7, as well as 4.1.0-M0 through 4.1.2. The lack of input validation on the server side during attribute storage combined with insufficient output encoding during CSV generation creates a persistent threat vector that persists until the data is either modified or deleted by an administrator.
The operational impact of this vulnerability extends beyond simple data corruption, as it facilitates remote code execution scenarios dependent on user interaction. An attacker who has obtained valid credentials can store the malicious payload in their own profile and then trigger an export operation, potentially through social engineering if they control other accounts or have influence over administrative workflows that involve exporting user lists. When a privileged user or administrator opens the exported CSV file to review data, the embedded formula executes automatically within the spreadsheet application's environment. This can lead to the execution of system commands, exfiltration of local files via DDE protocols, or further lateral movement if the compromised machine is part of a larger network infrastructure. The attack aligns with CWE-79 Improper Neutralization of Input During Web Page Generation in contexts where output encoding fails, and it maps to MITRE ATT&CK techniques related to Command and Scripting Interpreter execution via Office Applications.
Mitigation strategies must address both the immediate risk and long-term architectural resilience. Users are strongly advised to upgrade Apache Syncope to version 4.0.8 or 4.1.3 immediately, as these releases contain specific patches that enforce proper escaping of special characters during CSV export operations. In environments where upgrading is not immediately feasible, administrators should implement strict input validation on user-facing attributes to reject payloads containing formula delimiters such as equals signs, plus signs at the start of strings, or tab characters used in DDE attacks. Additionally, enabling macro security settings and configuring spreadsheet applications to disable automatic formula execution can provide a layer of defense-in-depth. Regular auditing of exported data formats and restricting CSV export permissions to only those users who strictly require it for operational purposes further reduces the attack surface by limiting exposure to this client-side code execution vector.