CVE-2026-111896 in phpMyFAQ
Summary
by MITRE • 10/17/2026
phpMyFAQ from 4.2.0-alpha before 4.2.0-beta contains a stored cross-site scripting vulnerability in SvgSanitizer that allows FAQ editors to store executable SVG files. Attackers can split script tags around removed tokens like processing instructions so single-pass removal reassembles them, executing script in the application origin when victims open the file.
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Analysis
by VulDB Data Team • 10/18/2026
The security flaw identified within phpMyFAQ versions prior to 4.2.0-beta represents a critical stored cross-site scripting vulnerability located specifically within the SvgSanitizer component. This issue arises from an insufficient validation and sanitization process applied to Scalable Vector Graphics files uploaded by users with editor privileges. The core technical deficiency lies in the logic used to strip potentially dangerous elements or attributes from SVG content, which relies on a single-pass removal strategy for specific tokens such as processing instructions. By exploiting this linear parsing approach, attackers can craft malicious SVG payloads that contain script tags fragmented across these removed sections. When the sanitizer removes the intervening token, it inadvertently concatenates the remaining parts of the script tag, effectively reconstructing executable JavaScript code within an otherwise benign-looking graphic file.
This vulnerability allows authenticated FAQ editors to persistently store these crafted SVG files on the server without immediate detection by the application's security controls. The severity is amplified because the stored content remains accessible and potentially renderable in subsequent sessions. When a victim user, such as another editor or administrator with access rights, opens or views the compromised file within the phpMyFAQ interface, the browser interprets the reassembled script tag and executes it. This execution occurs within the context of the application's origin, granting the attacker the ability to perform actions on behalf of the victim, steal session cookies, hijack administrative accounts, or manipulate the content displayed to other users. The stored nature of this attack means that a single successful upload can lead to multiple exploitation instances against different victims over time, significantly increasing the blast radius compared to reflected variants.
From an industry standard perspective, this vulnerability aligns with CWE-79, which classifies Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. Specifically, it demonstrates a failure in input validation where special characters and script delimiters are not adequately escaped or removed during the sanitization process. Furthermore, the exploitation technique relates to ATT&CK tactic TA0005 Defense Evasion through Obfuscated Indicators, as the attacker uses token splitting to bypass security filters that might otherwise block obvious malicious payloads. The use of SVG files also touches upon CWE-748 Improper Preservation of Vulnerable External Content Type, highlighting risks associated with allowing dynamic content types without rigorous structural validation.
To mitigate this risk, immediate action is required for all systems running phpMyFAQ versions from 4.2.0-alpha up to but not including 4.2.0-beta. Administrators should upgrade the software to version 4.2.0-beta or any later stable release where the SvgSanitizer logic has been corrected to handle multi-pass sanitization or more robust parsing strategies that prevent token reassembly attacks. In environments where immediate patching is not feasible, implementing a Web Application Firewall rule set capable of detecting fragmented script tag patterns in uploaded SVG files can provide an additional layer of defense. Additionally, enforcing strict Content Security Policy headers and disabling unnecessary editor privileges for users who do not require file upload capabilities can reduce the attack surface. Regular security audits focusing on input validation logic for complex data types like XML-based graphics are recommended to prevent similar bypass techniques in future updates.