CVE-2025-26756 identifies a stored cross-site scripting (XSS) vulnerability in the grimdonkey Magic the Gathering Card Tooltips plugin, specifically affecting versions up to and including 3.5.0. The vulnerability stems from improper neutralization of user-supplied input during the generation of web pages, allowing malicious scripts to be stored persistently within the application. When other users access the affected pages, the injected scripts execute in their browsers under the context of the vulnerable site. This type of vulnerability can be exploited to steal session cookies, perform actions on behalf of authenticated users, deface web content, or deliver malware. The plugin is used to enhance Magic the Gathering card tooltips on websites, which suggests its deployment in communities and platforms related to this game. No CVSS score has been assigned yet, and no known exploits have been reported in the wild, but the nature of stored XSS makes it a critical concern. The vulnerability does not require authentication or user interaction beyond visiting a compromised page, increasing its risk profile. The absence of official patches at the time of publication necessitates immediate attention to input validation and output encoding practices. The vulnerability was reserved and published in February 2025 by Patchstack, indicating active tracking by security researchers.

The stored XSS vulnerability in the Magic the Gathering Card Tooltips plugin can have severe consequences for affected organizations. Attackers can inject malicious scripts that execute in the browsers of users visiting compromised pages, leading to theft of sensitive information such as session tokens, personal data, or credentials. This can result in account takeover, unauthorized transactions, or further compromise of the affected web application. Additionally, attackers may use the vulnerability to deface websites, spread malware, or pivot to other internal systems. Because the vulnerability is stored, the malicious payload persists, increasing the window of exposure and potential damage. Organizations hosting communities or e-commerce platforms related to Magic the Gathering cards are particularly at risk, as their user base may be targeted. The impact extends to user trust and brand reputation, as exploitation can lead to public data breaches or service disruptions. The ease of exploitation without authentication or complex prerequisites amplifies the threat, making it a high-risk vulnerability for any site using the affected plugin.

To mitigate CVE-2025-26756, organizations should immediately implement strict input validation and output encoding on all user-supplied data processed by the Magic the Gathering Card Tooltips plugin. Employ context-aware escaping to neutralize any potentially malicious scripts before rendering content in browsers. Until an official patch is released, consider disabling or removing the plugin if feasible. Implement a robust Content Security Policy (CSP) that restricts the execution of inline scripts and limits sources of executable code to trusted domains. Regularly audit and sanitize existing stored data to remove any injected malicious scripts. Monitor web server and application logs for unusual activity or repeated injection attempts. Educate developers and administrators on secure coding practices related to XSS prevention. Finally, stay updated with vendor advisories and apply patches promptly once available to fully remediate the vulnerability.