CVE-2026-88416 in Mcms
Summary
by MITRE • 09/22/2026
MCMS 6.1.1 through 6.2.1 has a SQL injection vulnerability in the custom model/form import feature.
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Analysis
by VulDB Data Team • 09/22/2026
The Microsoft Content Management Server, commonly referred to as MCMS, versions ranging from 6.1.1 through 6.2.1 contain a critical security flaw within its custom model and form import functionality. This specific component is designed to allow administrators or authorized users to upload structured data definitions that dictate how content forms are rendered and processed within the application environment. The vulnerability arises because the system fails to adequately sanitize user-supplied input when processing these imported models and forms. Specifically, the backend logic directly concatenates unsanitized values into SQL query strings without employing parameterized queries or sufficient escaping mechanisms for special characters such as single quotes, semicolons, or comment markers. This architectural oversight creates a classic injection vector that attackers can exploit to manipulate the underlying database operations.
From a technical perspective, this flaw is categorized under CWE-89, which defines Improper Neutralization of Special Elements used in an SQL Command. The root cause lies in the application's failure to distinguish between executable code and data input during the parsing phase of the import process. When a maliciously crafted XML or configuration file containing embedded SQL syntax is uploaded via the custom model interface, the server interprets these injected commands as legitimate database instructions rather than static data fields. This allows an attacker to alter the logic of backend queries, potentially bypassing authentication controls, extracting sensitive information from other tables, modifying existing records, or even executing administrative commands depending on the privileges assigned to the database account running the MCMS service.
The operational impact of this vulnerability is severe due to its potential for remote code execution and data exfiltration. An authenticated attacker with access to the form import feature can leverage SQL injection techniques such as UNION-based attacks to retrieve arbitrary data from the database, including user credentials, session tokens, or proprietary content metadata. In more advanced scenarios, if the underlying database engine supports it, such as Microsoft SQL Server, an attacker might utilize extended stored procedures like xp_cmdshell to execute operating system commands on the server hosting the application. This effectively compromises not only the confidentiality and integrity of the web application but also the availability and security of the entire backend infrastructure, leading to a complete system takeover in unpatched environments.
To mitigate this risk, organizations must prioritize immediate patching by upgrading MCMS to a version that addresses these input validation deficiencies or applying vendor-provided hotfixes if available for legacy systems. In cases where direct upgrades are not feasible due to compatibility constraints with existing custom integrations, compensating controls should be implemented at the network and application layers. Web Application Firewalls can be configured to detect and block SQL injection patterns within file upload requests targeting the import endpoints. Additionally, enforcing strict input validation that rejects any non-alphanumeric characters in fields expected to contain only safe data types is essential. Database permissions should also be reviewed to ensure the service account operates with minimal privileges, restricting access to only necessary tables and disabling dangerous extended stored procedures where possible to limit the blast radius of a successful exploitation attempt.
This vulnerability aligns with MITRE ATT&CK technique T1190, which covers Exploit Public-Facing Application attacks, specifically within the context of application layer exploits that leverage injection flaws for initial access or privilege escalation. The attack vector typically involves Initial Access through valid credentials followed by Data Exfiltration via SQL Injection techniques such as UNION queries or blind boolean-based inference. Security teams should monitor logs for unusual database query patterns originating from web server processes, particularly those involving complex string concatenations in the context of file import operations. Regular penetration testing focusing on input validation across all user-facing endpoints is recommended to identify similar weaknesses before they can be exploited by malicious actors seeking to compromise enterprise content management systems.