CVE-2025-63848 identifies a stored cross-site scripting vulnerability in SWISH Prolog, a web-based Prolog environment used for interactive programming and educational purposes. The vulnerability exists in versions up to 2.2.0 and allows an attacker to inject malicious scripts into the web IDE notebook interface. Because the XSS is stored, the malicious payload persists on the server and executes whenever a user accesses the infected notebook, enabling arbitrary code execution within the victim's browser context. This can lead to session hijacking, credential theft, or further exploitation of the user's environment. The vulnerability arises from insufficient input validation or output encoding in the notebook interface, allowing crafted inputs to be stored and later rendered unsafely. No CVSS score or patch links are currently available, and no known exploits have been reported, indicating the vulnerability is newly disclosed. The attack vector requires the attacker to have the ability to submit crafted content to the web IDE, which may require authenticated access depending on deployment. The impact is significant due to the persistent nature of the stored XSS and the potential for arbitrary code execution in user browsers. SWISH Prolog is used primarily in academic, research, and development environments, which may have varying levels of security controls. The vulnerability highlights the need for secure coding practices in web-based development tools and the importance of sanitizing user inputs and outputs to prevent script injection.

For European organizations, especially universities, research institutions, and software development teams using SWISH Prolog, this vulnerability poses a risk of unauthorized code execution within user browsers. Attackers could leverage this to steal session tokens, impersonate users, or pivot to further attacks within the network. The persistent nature of stored XSS increases the risk of widespread compromise among users accessing the affected notebooks. Confidentiality is at risk due to potential data theft, integrity could be compromised by malicious script execution altering user data or interactions, and availability could be indirectly affected if attacks lead to denial of service or system instability. The impact is heightened in environments where sensitive research data or intellectual property is handled. Since the vulnerability affects a niche but critical tool in certain sectors, the overall scope is limited but significant within those contexts. The lack of known exploits suggests a window for proactive mitigation before widespread abuse occurs.

Organizations should immediately review their use of SWISH Prolog and restrict access to the web IDE notebook interface to trusted users only. Implement strict input validation and output encoding in the notebook interface to prevent script injection. Monitor and audit user-submitted content for suspicious inputs. Where possible, deploy web application firewalls (WAFs) with rules to detect and block XSS payloads targeting SWISH Prolog. Stay alert for official patches or updates from the SWISH Prolog maintainers and apply them promptly once available. Educate users about the risks of interacting with untrusted notebooks or links. Consider isolating the SWISH Prolog environment from critical infrastructure to limit potential lateral movement. Employ Content Security Policy (CSP) headers to reduce the impact of XSS by restricting script execution sources. Finally, conduct regular security assessments of web-based development tools to identify and remediate similar vulnerabilities proactively.