CVE-2023-44383 is a medium severity vulnerability classified as CWE-79, indicating an improper neutralization of input during web page generation, commonly known as a Cross-site Scripting (XSS) flaw. This vulnerability affects OctoberCMS, a popular content management system and web development platform. Specifically, the issue arises when a user with access to the media manager uploads or manages SVG files. SVG files can contain embedded scripts or malicious payloads. Due to insufficient sanitization or validation of SVG content, an attacker with media manager access can craft a stored XSS attack. This attack can execute malicious scripts in the context of any user who accesses the media manager, including the attacker themselves and other users with similar privileges. The vulnerability requires that the attacker has at least limited privileges (PR:L) and that the victim interacts with the malicious SVG file (UI:R). The CVSS 3.1 base score is 5.4, reflecting a medium severity with network attack vector (AV:N), low attack complexity (AC:L), partial impact on confidentiality and integrity (C:L/I:L), no impact on availability (A:N), and scope change (S:C). The vulnerability was patched in OctoberCMS version 3.5.2, and it affects versions from 3.0.0 up to but not including 3.5.2. There are no known exploits in the wild at the time of publication. The core technical issue is the failure to properly sanitize SVG content uploaded via the media manager, allowing embedded scripts to execute when the SVG is rendered in the media manager interface or other parts of the CMS that support SVG display. This can lead to session hijacking, privilege escalation, or unauthorized actions within the CMS environment.

For European organizations using OctoberCMS, this vulnerability poses a risk primarily to internal users with media manager access. If exploited, attackers could execute arbitrary scripts in the context of other users, potentially leading to session theft, unauthorized changes to content or configurations, and lateral movement within the CMS environment. This could compromise the integrity and confidentiality of website content and administrative data. Given that OctoberCMS is used by various businesses, including SMEs and agencies for website management, the impact could extend to customer data exposure or defacement of public-facing websites. While the vulnerability does not directly affect availability, the reputational damage and potential data breaches could have regulatory implications under GDPR, especially if personal data is exposed or manipulated. The requirement for at least limited privileges reduces the risk from external attackers but highlights the importance of internal user access controls. Organizations relying on OctoberCMS for critical web infrastructure should consider this vulnerability significant enough to warrant immediate patching to prevent exploitation.

1. Upgrade OctoberCMS installations to version 3.5.2 or later, where the vulnerability has been patched. 2. Restrict media manager access strictly to trusted users and review user roles to minimize the number of users with upload privileges. 3. Implement additional input validation and sanitization controls for SVG files, possibly using external sanitization libraries or services that strip scripts from SVG content before upload. 4. Monitor logs and user activity within the CMS for unusual behavior related to media uploads or access patterns. 5. Educate users with media manager access about the risks of uploading untrusted SVG files and enforce policies to only upload files from verified sources. 6. Consider disabling SVG support in the media manager if not required, or convert SVGs to safer formats before upload. 7. Regularly audit and update CMS plugins and dependencies to reduce the attack surface. 8. Employ Content Security Policy (CSP) headers to limit the impact of potential XSS attacks by restricting script execution contexts.