CVE-2026-84223 in Kirki Plugin
Summary
by MITRE • 09/20/2026
The Kirki WordPress plugin before 6.3.1 does not sanitize uploaded SVG files while making them uploadable site-wide, allowing users with author-level access and above to upload a file containing JavaScript which is then served from the site's own origin and runs in the session of anyone who opens it.
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Analysis
by VulDB Data Team • 09/20/2026
The vulnerability identified in Kirki versions prior to 6.3.1 represents a critical server-side request forgery and cross-site scripting risk stemming from inadequate input validation on file uploads. Specifically, the plugin fails to properly sanitize or validate SVG files when they are uploaded by users possessing author-level permissions or higher. This oversight allows an attacker with such privileges to bypass standard security controls that typically restrict executable content within image formats. By exploiting this flaw, a malicious actor can inject JavaScript code directly into the structure of an SVG file, effectively turning what should be a static graphic into a vehicle for executing arbitrary client-side scripts.
The operational impact of this vulnerability is severe due to the context in which the uploaded files are served. Once the compromised SVG file is successfully uploaded and stored on the server, it becomes accessible via a direct URL from the website's own domain. This means that when any user visits the page containing or linking to this malicious image, their browser will execute the embedded JavaScript within the security context of the target site. Because the script runs with the same origin as the main application, it inherits all associated cookies and session tokens. Consequently, an attacker can perform actions on behalf of authenticated users, steal sensitive data such as administrative credentials or personal information, deface the website by modifying its content through DOM manipulation, or redirect visitors to malicious external sites designed for phishing or malware distribution.
From a classification perspective, this issue aligns with CWE-20 Improper Input Validation and CWE-79 Cross-site Scripting (XSS). The root cause lies in the failure to enforce strict allow-listing of safe SVG elements and attributes while stripping out dangerous ones like script tags or event handlers such as onload. Furthermore, because the attack relies on a user with specific privileges initiating the upload, it also touches upon CWE-269 Improper Privilege Control, although the primary vector is input validation rather than privilege escalation itself. In terms of the MITRE ATT&CK framework, this vulnerability facilitates techniques associated with Stored Cross-Site Scripting and potentially Account Manipulation if used to escalate privileges or maintain persistence through injected admin-level scripts.
Mitigation strategies must focus on immediate remediation and long-term hardening. The most effective solution is to upgrade the Kirki plugin to version 6.3.1 or later, where these sanitization checks have been implemented. For organizations unable to patch immediately due to compatibility concerns with other plugins, a temporary workaround involves restricting file upload permissions for SVG files entirely through server-level configurations such as .htaccess rules on Apache servers or location blocks in Nginx configuration files. Additionally, implementing Content Security Policy headers can help mitigate the impact of any successfully injected scripts by restricting the sources from which executable content is allowed to load. Regular auditing of user roles and ensuring that only trusted administrators have upload capabilities further reduces the attack surface for this type of vulnerability.