CVE-2025-28102 is a cross-site scripting (XSS) vulnerability identified in flaskBlog version 2.6.1. This vulnerability arises from insufficient input sanitization of the 'postContent' parameter in the /createpost endpoint. An attacker can craft a malicious payload containing arbitrary web scripts or HTML and inject it into this parameter. When the vulnerable application processes and renders this input without proper encoding or sanitization, the malicious script executes in the context of the victim's browser. This can lead to session hijacking, defacement, or redirection to malicious sites. The vulnerability is classified under CWE-79, which covers improper neutralization of input during web page generation. According to the CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N), the attack can be performed remotely over the network without privileges but requires user interaction (the victim must visit the crafted page). The scope is changed, indicating the vulnerability can affect resources beyond the initially vulnerable component. The impact on confidentiality and integrity is low, while availability is unaffected. No known exploits are currently in the wild, and no patches have been released yet. The vulnerability was reserved on 2025-03-11 and published on 2025-04-21. The affected product is flaskBlog, an open-source blogging platform built on the Flask web framework, commonly used for small to medium web applications and personal blogs. The lack of vendor or product details beyond flaskBlog v2.6.1 limits precise attribution but indicates a niche target rather than widespread enterprise software.

For European organizations, the impact of this XSS vulnerability depends largely on the adoption of flaskBlog within their web infrastructure. Organizations using flaskBlog for internal or public-facing blogs risk attackers injecting malicious scripts that could steal user session tokens, perform phishing attacks, or manipulate displayed content. This could lead to reputational damage, unauthorized access to user accounts, and potential data leakage. Since the vulnerability requires user interaction, the risk is higher for organizations with large user bases or public-facing blogs where attackers can lure users to maliciously crafted posts. The scope change in the CVSS vector suggests that the vulnerability could be leveraged to affect other components or users beyond the initial vulnerable endpoint, potentially enabling broader compromise within the application context. However, the absence of known exploits and the medium severity rating indicate that while the threat is real, it is not currently widespread or critical. European organizations with strict data protection regulations (e.g., GDPR) must consider the confidentiality impact, even if low, as any data leakage or unauthorized access could lead to compliance issues and fines.

Given the nature of the vulnerability, specific mitigation steps include: 1) Immediate review and sanitization of all user-supplied input, especially the 'postContent' parameter, using robust server-side encoding libraries that neutralize HTML and JavaScript content before rendering. 2) Implement Content Security Policy (CSP) headers to restrict the execution of inline scripts and reduce the impact of potential XSS payloads. 3) Employ HTTPOnly and Secure flags on cookies to prevent theft via script access. 4) Conduct thorough code audits of all input handling in flaskBlog, focusing on other parameters that may be vulnerable. 5) Since no official patch is available, consider applying community-developed patches or temporarily disabling the /createpost functionality if feasible. 6) Educate users about the risks of clicking on suspicious links or posts, especially in environments where flaskBlog is used. 7) Monitor web application logs for unusual input patterns or error messages indicative of attempted exploitation. 8) For organizations deploying flaskBlog, consider migrating to alternative blogging platforms with active security maintenance if timely patches are not forthcoming.