CVE-2025-56423 is a vulnerability identified in the OpenAtlas software version 8.12.0, developed by the Austrian Archaeological Institute under the Austrian Academy of Sciences. The flaw arises from the application's handling of login error messages, which disclose sensitive information to remote attackers. Specifically, the system provides detailed feedback during failed login attempts that can reveal information about user accounts or authentication mechanisms, classified under CWE-203 (Information Exposure Through Discrepancy). The vulnerability is remotely exploitable without requiring any privileges or user interaction, as indicated by the CVSS vector (AV:N/AC:L/PR:N/UI:N). The impact is limited to confidentiality, with no direct effect on integrity or availability. The CVSS base score of 5.3 reflects a medium severity level. No patches or fixes have been released at the time of publication, and no known exploits exist in the wild. The vulnerability could be leveraged by attackers to enumerate valid usernames or gain insights into the authentication process, facilitating subsequent targeted attacks such as brute force or social engineering. Given the specialized nature of OpenAtlas, primarily used in archaeological research and academic environments, the threat is focused on institutions managing sensitive cultural heritage data. The vulnerability's disclosure date is November 24, 2025, with the CVE reserved earlier in August 2025.

For European organizations, particularly academic and research institutions using OpenAtlas software, this vulnerability poses a risk of sensitive information leakage. The disclosed information could enable attackers to identify valid user accounts or understand authentication workflows, increasing the likelihood of successful credential-based attacks. Although the vulnerability does not directly compromise system integrity or availability, the confidentiality breach could lead to unauthorized access if combined with other attack vectors. Institutions managing sensitive archaeological or cultural data could face reputational damage or data privacy concerns. The absence of known exploits reduces immediate risk, but the ease of remote exploitation without authentication means attackers could attempt automated scanning and enumeration. This risk is heightened in Austria and neighboring countries where OpenAtlas adoption is more prevalent. The vulnerability could also attract interest from threat actors targeting European cultural heritage or academic networks for espionage or sabotage.

Organizations should immediately review and modify the OpenAtlas login error handling to avoid disclosing sensitive information. This includes standardizing error messages to generic responses that do not reveal whether a username exists or the nature of the authentication failure. Network-level controls such as rate limiting and IP blacklisting should be implemented to prevent automated enumeration attempts. Monitoring authentication logs for unusual patterns or repeated failed login attempts can help detect exploitation attempts early. Since no official patch is available, organizations should engage with the software vendor or maintainers to prioritize a fix. In parallel, multi-factor authentication (MFA) should be enforced to reduce the risk of compromised credentials. Conducting security awareness training for users about phishing and credential security is also recommended. Finally, organizations should consider isolating OpenAtlas systems within segmented network zones to limit exposure.