CVE-2026-73387 in Resido Plugin
Summary
by MITRE • 08/19/2026
Unauthenticated Local File Inclusion in Resido <= 1.5 versions.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified as an unauthenticated local file inclusion flaw within Resido version 1.5 and earlier represents a critical security deficiency that allows attackers to read arbitrary files from the server's filesystem without requiring any form of authentication or user interaction. This type of vulnerability typically arises when a web application accepts unsanitized input parameters, such as those passed via URL query strings or POST data, and directly incorporates them into file system operations like include statements in PHP-based applications. In the specific context of Resido, which is often deployed for property rental management, this flaw likely stems from improper validation of user-supplied filenames or paths that are subsequently used to load configuration files, templates, or other resources. Because no authentication mechanism is required to exploit this issue, any remote attacker with network access to the target server can leverage this weakness, significantly lowering the barrier to entry for malicious actors and increasing the likelihood of successful exploitation in unpatched environments.
From a technical perspective, local file inclusion vulnerabilities occur when an application fails to properly validate or sanitize user input before using it as part of a dynamic file path. If the underlying code constructs a file path by concatenating user-controlled data with a base directory without checking for directory traversal sequences such as dot-dot-slash, attackers can manipulate these inputs to escape the intended directory structure and access sensitive files located elsewhere on the server. This capability is particularly dangerous because it bypasses standard web application firewalls that might otherwise block direct requests to protected directories if they do not recognize the specific inclusion mechanism being abused. The lack of authentication means that even users with no prior knowledge of valid credentials can probe the system, making this a high-severity risk for any publicly accessible instance of the software.
The operational impact of exploiting an unauthenticated local file inclusion vulnerability is severe and multifaceted. Initially, attackers can read sensitive configuration files such as database connection strings, API keys, or administrative passwords stored in plain text within config.php or similar files. This information disclosure provides the necessary credentials to escalate privileges further into a full system compromise. Beyond simple data theft, if the server environment allows for remote file inclusion through specific PHP configurations like allow_url_include being enabled, attackers might be able to inject malicious code from external servers, leading to arbitrary command execution and complete control over the web server. Even in restricted environments where only local files can be included, reading critical system logs or source code can reveal additional architectural weaknesses that facilitate subsequent attacks such as SQL injection or cross-site scripting.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-98 Improper Control of Filename for Include Statement and is often categorized under the broader class of CWE-200 Information Exposure. In terms of offensive security frameworks, this exploit falls under MITRE ATT&CK technique T1537 which involves accessing remote shared resources to gather information or facilitate further attacks. The absence of authentication requirements places it in a high-risk category similar to CVEs affecting widely used content management systems where default configurations often leave such endpoints exposed. Organizations running Resido must recognize that this is not merely an informational leak but a potential gateway for total system takeover, requiring immediate remediation efforts.
Mitigation strategies should focus on both immediate patching and long-term architectural improvements. The primary recommendation is to upgrade the Resido installation to version 1.6 or later where these inclusion flaws have been addressed by developers through proper input validation and path canonicalization techniques. For systems that cannot be immediately upgraded, administrators can implement web application firewall rules specifically designed to detect and block directory traversal patterns in URL parameters related to file includes. Additionally, server-side hardening measures such as disabling allow_url_include in PHP configuration files reduce the risk of remote code execution via inclusion vectors. It is also advisable to restrict file permissions so that even if a sensitive file like config.php is included, its contents are not directly rendered or executed by the web server process unless absolutely necessary for application functionality. Regular security audits and static code analysis should be employed to identify similar patterns in custom modules or plugins associated with Resido to ensure comprehensive protection against this class of vulnerabilities.