CVE-2026-2499 is a stored cross-site scripting (XSS) vulnerability identified in the tgrk Custom Logo plugin for WordPress, affecting all versions up to and including 2.2. The vulnerability arises from improper neutralization of input during web page generation, specifically due to insufficient input sanitization and output escaping in the plugin's admin settings. This flaw allows authenticated users with administrator-level permissions or higher to inject arbitrary JavaScript code into pages. The injected scripts execute whenever any user accesses the compromised page, potentially enabling session hijacking, privilege escalation, or other malicious activities. Notably, this vulnerability only affects WordPress multi-site installations or those where the unfiltered_html capability is disabled, limiting its scope. The CVSS 3.1 base score is 4.4 (medium severity), reflecting that exploitation requires network access, high complexity, and high privileges, but no user interaction. The vulnerability impacts confidentiality and integrity but not availability, and the scope is changed due to the multi-site context. No public exploits have been reported yet, but the presence of administrator-level access as a prerequisite means that attackers must already have significant control over the environment to leverage this vulnerability. The lack of patch links indicates that a fix may not yet be publicly available, emphasizing the need for interim mitigations.

The primary impact of CVE-2026-2499 is the potential execution of arbitrary scripts within the context of affected WordPress multi-site installations using the tgrk Custom Logo plugin. This can lead to theft of sensitive information such as authentication cookies, enabling session hijacking or impersonation of users. It may also allow attackers to modify content or perform actions on behalf of other users, undermining data integrity. Since exploitation requires administrator-level privileges, the vulnerability is less likely to be exploited by external attackers without prior access, but it poses a significant risk if an insider or compromised admin account is involved. The multi-site environment increases the potential blast radius, as injected scripts can affect multiple sites within the network. Although availability is not impacted, the confidentiality and integrity risks can lead to reputational damage, data breaches, and further compromise of the WordPress environment. Organizations relying on this plugin in multi-site configurations should consider this a moderate threat that could facilitate more severe attacks if combined with other vulnerabilities or credential compromises.

To mitigate CVE-2026-2499, organizations should first verify if they are running multi-site WordPress installations with the tgrk Custom Logo plugin version 2.2 or earlier. Immediate mitigation steps include restricting administrator-level access to trusted personnel only and auditing existing admin accounts for suspicious activity. Since no official patch is currently available, consider disabling or removing the Custom Logo plugin temporarily in multi-site environments where unfiltered_html is disabled. Implement additional input validation and output escaping at the application level if feasible. Employ Web Application Firewalls (WAFs) with custom rules to detect and block suspicious script injections targeting the plugin's admin settings. Regularly monitor logs for anomalous admin actions or unexpected script insertions. Educate administrators about the risks of XSS and the importance of secure plugin management. Once a patch is released, prioritize timely updates. Additionally, consider enabling Content Security Policy (CSP) headers to restrict script execution origins, reducing the impact of potential XSS attacks.