CVE-2026-84793 in cms
Summary
by MITRE • 09/02/2026
Craft CMS versions from 5.0.0-RC1 before 5.10.11 contain a stored cross-site scripting vulnerability in the site name field that fails to sanitize input. Administrators can inject arbitrary JavaScript payloads in the site name that execute when other users view the control panel settings pages.
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Analysis
by VulDB Data Team • 09/02/2026
Craft CMS versions ranging from 5.0.0-RC1 up to, but not including, version 5.10.11 are affected by a critical stored cross-site scripting vulnerability located within the site name configuration field. This security flaw arises because the application fails to adequately sanitize or encode user-supplied input before storing it in the database and subsequently rendering it back into the HTML response without proper context-aware escaping. The vulnerability is classified as CWE-79, which denotes Improper Neutralization of Input During Web Page Generation, commonly known as cross-site scripting. Because the malicious script is stored on the server side rather than being passed via a single request parameter, this specific instance falls under the category of persistent or stored XSS, where the payload remains active until manually removed from the database by an administrator.
The operational impact of this vulnerability is significant due to its potential for widespread exploitation within administrative interfaces. An attacker with access to create or modify site configurations can inject arbitrary JavaScript payloads into the site name field. These scripts are then executed automatically whenever any user, including other administrators, views the control panel settings pages where the site information is displayed. This execution context grants the injected script full access to the browser session of the viewing user, potentially allowing for cookie theft, session hijacking, credential harvesting, or redirection to malicious phishing sites. Since Craft CMS relies heavily on its administrative interface for content management and system configuration, compromising this area can lead to a complete takeover of the web application environment if valid administrator credentials are obtained through such attacks.
From an offensive security perspective, this vulnerability aligns with MITRE ATT&CK technique T1059.007, which covers JavaScript execution within browser environments for initial access or credential theft. The persistence mechanism inherent in stored XSS allows attackers to maintain long-term access without needing repeated exploitation attempts, as the payload executes on every page load that references the compromised site name data. This characteristic makes it particularly dangerous compared to reflected XSS variants, where user interaction with a specific link is required each time for execution.
Mitigation strategies must prioritize immediate patching and input validation enhancements. Administrators running affected versions should upgrade Craft CMS to version 5.10.11 or later as soon as possible, as this release includes the necessary fixes for input sanitization in the site name field. In environments where upgrading is not immediately feasible, temporary mitigations include implementing strict Content Security Policy headers that restrict script execution from unauthorized sources and ensuring that any custom plugins or themes do not bypass existing output encoding mechanisms. Additionally, developers should review all user-facing inputs across the application to ensure consistent implementation of context-aware escaping techniques, adhering to OWASP guidelines for preventing cross-site scripting attacks by validating input on both client and server sides while relying primarily on robust server-side sanitization before rendering data in HTML contexts.