CVE-2026-58143 in Siena
Summary
by MITRE • 07/10/2026
Cotonti Siena 0.9.26 and earlier contains a cross-site request forgery vulnerability that allows unauthenticated attackers to modify administrator configuration by tricking a logged-in administrator into submitting a forged POST request to the admin.php config update handler, which never invokes the application's CSRF validation function. Attackers can disable the PFS module's file extension whitelist by setting pfsfilecheck to 0, enabling any user with PFS access to upload and execute arbitrary PHP files on the server.
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Analysis
by VulDB Data Team • 07/10/2026
This cross-site request forgery vulnerability in Cotonti Siena versions 0.9.26 and earlier represents a critical security flaw that undermines the application's administrative controls and exposes servers to remote code execution risks. The vulnerability stems from the absence of proper CSRF protection mechanisms within the admin.php configuration update handler, allowing unauthenticated attackers to manipulate administrative settings through deceptive means. When a logged-in administrator visits a malicious page or clicks on a crafted link, their browser automatically submits a forged POST request that modifies system configurations without proper validation. This flaw falls under CWE-352, which specifically addresses Cross-Site Request Forgery vulnerabilities in software applications.
The technical implementation of this vulnerability exploits the trust relationship between the web application and its administrators. The admin.php endpoint responsible for handling configuration updates fails to invoke the application's built-in CSRF validation function, creating an exploitable gap in the security model. Attackers can leverage this weakness by crafting malicious requests that target the configuration update handler, specifically manipulating the pfsfilecheck parameter. When this parameter is set to 0, the system disables the PFS module's file extension whitelist functionality, effectively removing critical file validation controls. This modification creates a pathway for arbitrary PHP file uploads and executions, as demonstrated in the ATT&CK framework under technique T1505.003 for Server Software Component.
The operational impact of this vulnerability extends far beyond simple configuration changes, as it enables full compromise of affected systems through the PFS module's file upload capabilities. Once attackers disable the file extension whitelist, they can upload malicious PHP files to the server and execute them with administrative privileges, potentially leading to complete system takeover. The vulnerability affects all administrators who maintain active sessions, making it particularly dangerous in environments where multiple administrators access the system simultaneously. This scenario aligns with ATT&CK technique T1078.004 for Valid Accounts, as attackers can leverage existing administrator sessions rather than requiring additional authentication. The risk is compounded by the fact that many administrators may not be immediately aware of the configuration changes, as the attack occurs without their explicit consent or knowledge.
Mitigation strategies must address both immediate remediation and long-term security improvements to protect against similar vulnerabilities in Cotonti Siena and other web applications. Organizations should implement robust CSRF protection mechanisms across all administrative endpoints, including proper token validation and request origin verification. The application should be updated to version 0.9.27 or later where this vulnerability has been patched, as the developers have addressed the missing CSRF validation function invocation. Additionally, implementing proper input sanitization and validation for all configuration parameters, along with monitoring for unauthorized configuration changes, provides defense-in-depth measures. Security controls should include regular security assessments to identify similar CSRF vulnerabilities in custom code, as well as network-based intrusion detection systems that can monitor for suspicious administrative activity patterns. The vulnerability demonstrates the importance of following secure coding practices and implementing comprehensive validation mechanisms, particularly for critical administrative functions that could enable remote code execution when compromised.