CVE-2026-78190 in WebDyne
Summary
by MITRE • 10/31/2026
WebDyne versions from 2.014 before 3.022 for Perl reflect request parameters unescaped into form field values, allowing cross-site scripting.
The textfield, password_field and filefield tags fill their value attribute from the request parameter of the same name. WEBDYNE_CGI_AUTOESCAPE, which controls escaping of these values, defaults to off. From 2.022, WebDyne::HTML::Tiny also replaced its entity_encode method with one that returns its input unchanged, so enabling WEBDYNE_CGI_AUTOESCAPE has no effect.
A remote attacker can inject script into any page using these tags through a crafted link.
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Analysis
by VulDB Data Team • 10/31/2026
The vulnerability identified in WebDyne versions ranging from 2.014 to just before 3.022 represents a critical cross-site scripting flaw rooted in the framework's handling of user-supplied input within form elements. This issue specifically affects the textfield, password_field, and filefield tags, which are designed to populate their value attributes using request parameters that share the same name as the tag itself. The core technical failure lies in the fact that these values are reflected into the HTML output without proper escaping or sanitization. Under normal secure configurations, input data should be encoded to prevent it from being interpreted as executable code by the browser. However, due to the default configuration and implementation details of WebDyne during this version range, user-controlled parameters are inserted directly into the DOM structure, creating a direct vector for script injection.
A significant contributing factor to the severity and persistence of this vulnerability is the behavior of the WEBDYNE_CGI_AUTOESCAPE setting, which controls whether these values should be automatically escaped before rendering. By default, this security feature is disabled, meaning that even if an administrator attempts to rely on framework-level protections, they are ineffective unless explicitly enabled. Furthermore, a critical implementation defect introduced in version 2.022 exacerbates the problem by replacing the entity_encode method with one that returns its input unchanged regardless of configuration settings. This means that enabling WEBDYNE_CGI_AUTOESCAPE has no practical effect on preventing injection because the underlying encoding mechanism is broken and fails to transform special characters into their safe HTML entities. Consequently, any request parameter reflected into these form fields remains in its raw, executable state within the generated page source.
The operational impact of this vulnerability allows a remote attacker to execute arbitrary JavaScript code in the context of the victim's browser session. By crafting a malicious link that includes specially constructed query parameters targeting textfield, password_field, or filefield tags, an attacker can inject scripts into any page utilizing these components. This capability enables a range of attacks including session hijacking through cookie theft, credential harvesting by capturing user input in real-time, defacement of the web application interface, and potentially serving as a vector for further malware distribution via drive-by downloads. Since password fields are also affected, attackers can intercept sensitive authentication data directly from forms where users enter their credentials, leading to severe compromise of account security and potential unauthorized access to backend systems or user accounts associated with the vulnerable application.
From a classification perspective, this vulnerability aligns with CWE-79: Improper Neutralization of Input During Web Page Generation, commonly known as Cross-Site Scripting (XSS). Specifically, it falls under the reflected variant where malicious scripts are provided by an attacker and executed immediately without being saved to a database. In terms of offensive security frameworks, this maps directly to MITRE ATT&CK technique T1059: Command and Scripting Interpreter, with sub-techniques related to JavaScript execution within web browsers (T1059.007). The attack vector is classified as remote via the network, requiring no authentication if the application does not restrict access to the affected pages, making it a high-risk public-facing vulnerability that demands immediate remediation.
To mitigate this risk, organizations running WebDyne versions between 2.014 and 3.022 must upgrade immediately to version 3.022 or later where these issues have been addressed in subsequent releases. If upgrading is not immediately feasible, administrators should ensure that WEBDYNE_CGI_AUTOESCAPE is explicitly enabled in the configuration files, although they must be aware of the known bug in versions starting from 2.022 where this setting may fail to function correctly due to the broken entity_encode method. In such cases, manual input validation and output encoding at the application logic level are necessary as a compensating control. Developers should implement strict whitelisting for allowed characters in form fields or apply robust HTML escaping functions that properly convert special characters like ampersands, quotes, angle brackets, and slashes into their corresponding HTML entities before rendering them in the response body. Regular security audits and static code analysis tools configured to detect reflected XSS patterns are also recommended to identify similar flaws across other parts of the application architecture.