CVE-2026-86610 in Download Manager Plugin
Summary
by MITRE • 10/01/2026
The Download Manager WordPress plugin before 3.3.71 does not sufficiently sanitise and escape a package setting before outputting it back in a page, which could allow users with the Author role and above to perform Stored Cross-Site Scripting attacks against any visitor who opens the package's download dialogue, including administrators. Only sites running PHP below 8.1 are affected, as the sanitisation applied when the setting is saved does not neutralise single quotes there.
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified in versions of the Download Manager WordPress plugin prior to release 3.3.71 represents a significant security risk rooted in inadequate input validation and output encoding mechanisms. This flaw specifically affects sites operating on PHP environments below version 8.1, where the sanitization logic applied during data persistence fails to neutralize single quote characters. The core technical deficiency lies in the handling of package settings within the plugin's administrative interface. When an administrator or user with elevated privileges configures a download package, the input is not sufficiently sanitized before being stored in the database. Subsequently, when this data is retrieved and rendered back into the browser for display purposes, it is also not properly escaped. This dual failure creates a classic vector for Stored Cross-Site Scripting attacks, allowing malicious scripts to be embedded within legitimate content that persists on the server until manually removed or overwritten.
From an operational perspective, the impact of this vulnerability extends beyond simple data corruption or defacement. Because the flaw allows for stored cross-site scripting, any user with the Author role or higher can inject executable JavaScript code into a package setting. This malicious payload is then served to every visitor who interacts with the affected download dialogue. The attack scenario typically involves an attacker creating or modifying a download link where the associated metadata contains crafted script tags. When a victim, including high-privilege users such as administrators, opens this dialog to view details or initiate a download, their browser executes the injected code in the context of the vulnerable website. This can lead to session hijacking, credential theft via keyloggers, redirection to phishing sites, or further exploitation of other vulnerabilities present on the same domain through cross-site request forgery techniques facilitated by the stolen sessions.
The restriction to PHP versions below 8.1 highlights a nuanced aspect of this vulnerability's exploitability. In newer PHP environments, certain internal handling mechanisms or default behaviors might inadvertently mitigate some aspects of quote-based injection vectors, but in older versions, the lack of explicit sanitization for single quotes leaves the door open for attackers to break out of HTML attribute contexts and inject arbitrary script elements. This specificity underscores the importance of maintaining up-to-date server-side environments alongside application-level patches. The vulnerability aligns with CWE-79, which classifies improper neutralization of input during web page generation as a common cause of cross-site scripting flaws. It also maps to MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution, illustrating how attackers leverage client-side scripts to compromise system integrity and confidentiality within the application's trust boundary.
Mitigation strategies must address both immediate remediation and long-term security hygiene. The primary defense is upgrading the Download Manager plugin to version 3.3.71 or later, where the developers have implemented robust sanitization and escaping routines for all user-controlled inputs before database storage and subsequent output rendering. Administrators should also ensure that their WordPress installation and PHP environment are updated to supported versions, as running outdated software increases exposure to a wider range of known vulnerabilities. Additionally, implementing Content Security Policy headers can provide an additional layer of defense by restricting the sources from which scripts can be loaded or executed, thereby mitigating the impact even if a stored XSS vector is successfully injected. Regular security audits and code reviews focusing on input validation patterns are essential for preventing similar flaws in custom plugins or themes that may follow analogous development practices without adequate safeguards against injection attacks.