CVE-2026-114407 in e107
Summary
by MITRE • 10/21/2026
e107 CMS before 2.3.13 contains a reflected cross-site scripting vulnerability that allows unauthenticated attackers to inject malicious HTML by manipulating the author GET parameter in search.php, which is parsed with parse_str() and concatenated unescaped into a rendered input tag via the form handler's 'other' option key. Attackers can craft a single GET request containing a crafted author parameter to break out of the HTML input tag and inject an img element with an onerror handler, executing arbitrary JavaScript in the victim's browser session.
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Analysis
by VulDB Data Team • 10/21/2026
The vulnerability identified in e107 CMS versions prior to 2.3.13 represents a classic reflected cross-site scripting flaw rooted in improper input validation and output encoding within the application search functionality. The core technical defect lies in how the system processes user-supplied data from the HTTP GET request, specifically targeting the author parameter passed through the search.php script. Upon receiving this input, the server-side code utilizes the parse_str function to decode URL-encoded parameters into variables. While parsing is a standard procedure for handling query strings, it does not inherently sanitize or encode special characters that have semantic meaning in HTML contexts. The critical failure occurs when these parsed values are subsequently concatenated directly into an HTML form element without any escaping mechanism. This lack of proper output encoding allows malicious payloads to bypass the intended structure of the web page and inject executable script code directly into the browser's rendering engine.
From a technical perspective, the exploitation vector relies on breaking out of the context of an input tag by injecting specific HTML tags that trigger event handlers. An attacker crafts a specially constructed URL where the author parameter contains a payload such as an img element with an onerror attribute. When the victim clicks this link or is redirected to it via phishing techniques, their browser parses the injected markup. The image fails to load due to its invalid source, triggering the onerror event handler which executes the embedded JavaScript code within the context of the vulnerable site's domain. This execution environment grants the attacker significant capabilities, including access to session cookies, local storage data, and the ability to perform actions on behalf of the authenticated user if they are logged in at that moment.
The operational impact of this vulnerability is substantial because it enables unauthenticated attackers to compromise user sessions without requiring prior authentication credentials. By executing arbitrary JavaScript, an attacker can steal sensitive information such as session tokens, which could lead to account takeover. Furthermore, the vulnerability facilitates broader attack chains including phishing attacks where malicious forms are injected to harvest additional credentials or redirect users to external malicious sites. The reflected nature of this XSS means that each successful exploitation requires a user interaction with a crafted link, making social engineering a necessary component for initial access but allowing for widespread impact if distributed effectively through spam or compromised websites.
This vulnerability aligns closely with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it falls under the subcategory of Reflected XSS where the malicious script is part of a request sent to the web server and then reflected back in the response without proper sanitization. In terms of offensive security frameworks, this technique maps directly to MITRE ATT&CK tactic T1059, specifically command and scripting interpreter via browser-based execution using event handlers like onerror or onload attributes found within HTML tags. The use of parse_str combined with direct concatenation highlights a failure in implementing secure coding practices regarding data validation and context-aware output encoding.
To mitigate this vulnerability, developers must implement strict input validation to ensure that the author parameter only contains expected character sets such as alphanumeric characters and basic punctuation if names are allowed. More importantly, all user-supplied data rendered into HTML contexts must be properly encoded using appropriate functions provided by the framework or language, ensuring that special characters like angle brackets and quotes are converted to their corresponding HTML entities before being inserted into the DOM. Upgrading e107 CMS to version 2.3.13 or later resolves this issue as it includes patches for these input handling flaws. Additionally, implementing Content Security Policy headers can provide a layer of defense by restricting the sources from which scripts are allowed to execute, thereby mitigating the impact even if an injection attempt succeeds.