CVE-2026-102778 in Event Gallery Extension
Summary
by MITRE • 10/05/2026
Joomla Extension - svenbluege.de - Cross-site scripting and open redirect on the share mini page in Event Gallery extension < 6.6.0 - The page a shared image link opens (the share mini page of the front end) can link the article the image was shared from when the option "Share article links" is on. It took the address of the article from the shared link and printed it into the page without checking or escaping it; with the link type "Image Page with Redirect" it followed the address at once. A prepared link could therefore run a script in the page, in the session of the visitor who opened it, or send the visitor to another web site. Nothing on the server is changed or read by the server.
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Analysis
by VulDB Data Team • 10/05/2026
The vulnerability identified within the Event Gallery extension for Joomla versions prior to 6.6.0 represents a significant security flaw involving both Cross-Site Scripting and open redirect capabilities. This issue resides specifically in the share mini page functionality of the front-end interface, which is designed to display shared image links. The core technical failure stems from an improper validation mechanism when handling user-supplied input derived from shared link parameters. Specifically, when the configuration option for sharing article links is enabled, the application extracts the address of the source article directly from the provided URL and injects it into the HTML output without performing any necessary sanitization or escaping procedures. This lack of input validation allows an attacker to manipulate the data flow by injecting malicious payloads that are executed within the context of the victim's browser session.
From a technical perspective, this flaw is classified as Cross-Site Scripting under CWE-79 and open redirect under CWE-601. The vulnerability manifests in two distinct but related ways depending on the configured link type settings. In scenarios where the link type is set to Image Page with Redirect, the application immediately follows the unvalidated address provided in the shared link. This behavior facilitates an open redirect attack, allowing attackers to deceive users into visiting malicious third-party websites by disguising the destination within a trusted domain URL structure. Alternatively, if the configuration allows for script execution rather than immediate redirection, the injected code runs directly in the victim's browser context. Because this occurs on the front end and does not involve server-side data modification or reading, it is categorized as a reflected XSS vulnerability where the malicious payload is delivered via the URL parameter and executed upon page load by the client application.
The operational impact of this vulnerability is substantial for both site administrators and their users. For end-users, an open redirect can be leveraged in phishing campaigns to direct victims to credential harvesting sites that mimic legitimate login pages, thereby facilitating account compromise through social engineering. If the XSS vector is exploited successfully, attackers can execute arbitrary JavaScript code within the victim's session. This capability enables a range of malicious activities including session hijacking, where the attacker steals authentication cookies or tokens to impersonate the user; keylogging to capture sensitive input data such as passwords and credit card numbers; or defacement by modifying the visual presentation of the page. Since the vulnerability relies on the victim clicking a specially crafted link shared via email, social media, or other communication channels, it requires no prior authentication from the attacker but does require interaction from the user, which is typical for reflected XSS attacks.
Mitigation strategies must address both the immediate technical flaw and broader security hygiene practices. The primary remediation involves upgrading the Event Gallery extension to version 6.6.0 or later, where these input validation issues have been resolved by implementing proper output encoding and URL validation mechanisms. For organizations unable to upgrade immediately due to compatibility constraints, a temporary workaround is to disable the Share article links option within the Joomla backend configuration if this feature is not strictly required for business operations. This effectively neutralizes the attack vector by preventing the application from processing untrusted input in that specific context. Additionally, implementing Content Security Policy headers can help mitigate the impact of any successful XSS attempts by restricting the sources from which scripts are allowed to execute. Regular security audits and penetration testing should be conducted on third-party Joomla extensions to ensure they adhere to secure coding standards such as OWASP Top Ten guidelines, particularly regarding input validation and output encoding requirements.