CVE-2025-67634 is a cross-site scripting vulnerability classified under CWE-79, affecting the CISA Software Acquisition Guide Tool prior to version 2025-12-11. The vulnerability stems from improper neutralization of input during web page generation, specifically in text fields that accept JSON data imports. An attacker can craft a malicious JSON file containing embedded JavaScript code. When a user imports this file into the tool and clicks the 'Next' button to submit the page, the JavaScript executes within the user's browser context. This execution can lead to unauthorized actions such as session hijacking, data theft, or manipulation of the web application interface. The attack vector requires the attacker to convince the user to import the malicious JSON file, indicating a need for social engineering or insider threat scenarios. The CVSS v4.0 score is 4.6 (medium severity), reflecting local attack vector (AV:L), low complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:A). The impact on confidentiality and integrity is low, with no impact on availability. No patches or exploits are currently documented, but the vulnerability is publicly disclosed as of December 12, 2025.

For European organizations, the impact of this vulnerability is moderate but non-trivial. Since the CISA Software Acquisition Guide Tool is used for software procurement and supplier evaluation, exploitation could lead to unauthorized disclosure or manipulation of sensitive procurement data. Attackers could leverage this XSS flaw to execute scripts that steal session tokens or manipulate displayed information, potentially influencing procurement decisions or exposing confidential supplier responses. The requirement for user interaction and local access reduces the risk of widespread automated attacks but increases the threat from targeted phishing or insider threats. Organizations involved in critical infrastructure procurement or government-related software acquisition in Europe could face reputational damage or operational disruption if exploited. The vulnerability does not directly affect system availability but could undermine trust in procurement processes and data integrity.

European organizations should implement the following specific mitigations: 1) Immediately update the CISA Software Acquisition Guide Tool to the fixed version released after 2025-12-11 once available. 2) Until patches are applied, restrict access to the tool to trusted users only and enforce strict user training to avoid importing untrusted JSON files. 3) Implement Content Security Policy (CSP) headers to limit the execution of inline scripts and reduce the impact of XSS attacks. 4) Employ input validation and sanitization on all JSON imports, ensuring that scripts or executable code cannot be embedded. 5) Monitor user activity logs for unusual import actions or repeated failed attempts to import files. 6) Use browser security features such as XSS filters and disable unnecessary scripting capabilities where feasible. 7) Conduct phishing awareness campaigns to reduce the risk of social engineering attacks that could trick users into importing malicious files. 8) Consider network segmentation to isolate the tool from broader enterprise systems to limit lateral movement in case of compromise.