CVE-2025-40708 is a Cross-Site Scripting (XSS) vulnerability identified in version 8.9.0 of OpenAtlas, a software product developed by the Austrian Centre for Digital Humanities and Cultural Heritage (ACDH-CH). The vulnerability arises from improper neutralization of user input during web page generation, specifically within the handling of POST requests to the "/insert/event" endpoint, targeting the "name" parameter. Due to insufficient input validation and sanitization, an authenticated remote attacker can craft malicious payloads that, when processed by the vulnerable application, result in the execution of arbitrary scripts in the context of the victim user's browser. This can lead to the theft of session cookies and potentially other sensitive information, enabling session hijacking or further exploitation. The vulnerability requires the attacker to send a specially crafted request that is then processed by an authenticated user, implying that user interaction is necessary. The CVSS v4.0 base score is 5.1, categorized as medium severity, reflecting the moderate impact and the requirement for user interaction and privileges. No known exploits have been reported in the wild as of the publication date (August 29, 2025). The vulnerability is classified under CWE-79, which covers improper neutralization of input leading to XSS attacks. The scope of the vulnerability is limited to OpenAtlas version 8.9.0, and no patches or fixes have been linked yet. The attack vector is network-based, with low attack complexity, no privileges required to initiate the attack, but requires user interaction and some privileges on the victim side. The vulnerability does not impact confidentiality, integrity, or availability directly but compromises session confidentiality through cookie theft, which can lead to further unauthorized access.

For European organizations using OpenAtlas 8.9.0, particularly those involved in digital humanities and cultural heritage sectors, this vulnerability poses a risk of session hijacking and unauthorized access to sensitive data. Since OpenAtlas is used for managing cultural heritage data, exploitation could lead to unauthorized data exposure, manipulation, or disruption of research activities. The requirement for an authenticated user to interact with a malicious payload means insider threats or targeted phishing campaigns could be effective attack vectors. The impact is heightened in environments where OpenAtlas is integrated with other sensitive systems or where session cookies grant elevated privileges. Additionally, the theft of session cookies could facilitate lateral movement within networks, potentially exposing broader organizational assets. The vulnerability could also undermine trust in digital cultural heritage platforms, affecting public-facing services and collaborations across European institutions. Given the medium severity and the specialized user base, the impact is significant but not catastrophic, emphasizing the need for timely mitigation to prevent exploitation.

1. Immediate mitigation should focus on implementing robust input validation and output encoding for the "name" parameter in the "/insert/event" POST request to neutralize malicious scripts. 2. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in the browser context. 3. Enforce secure cookie attributes such as HttpOnly and Secure to reduce the risk of cookie theft via XSS. 4. Conduct user awareness training to recognize and avoid phishing attempts that could deliver malicious payloads to authenticated users. 5. Limit user privileges in OpenAtlas to the minimum necessary to reduce the impact of compromised sessions. 6. Monitor application logs and network traffic for unusual POST requests to the vulnerable endpoint. 7. Since no official patch is currently available, organizations should consider temporary workarounds such as web application firewalls (WAF) with rules to detect and block suspicious input patterns targeting the "name" parameter. 8. Plan for timely application updates once a patch is released by ACDH-CH. 9. Review session management policies to shorten session lifetimes and implement multi-factor authentication to mitigate session hijacking risks.