CVE-2025-56423: OpenAtlas Information Disclosure Flaw

CVE-2025-56423 Overview

CVE-2025-56423 is an information disclosure vulnerability in OpenAtlas v8.12.0, a research database maintained by the Austrian Archaeological Institute of the Austrian Academy of Sciences. The application returns distinguishable error messages on the login form, allowing a remote unauthenticated attacker to enumerate valid usernames. The flaw is classified under CWE-203: Observable Discrepancy and stems from the login response revealing whether an account exists.

Critical Impact

Unauthenticated remote attackers can enumerate valid user accounts, providing a foundation for credential stuffing, password spraying, and targeted phishing campaigns against OpenAtlas users.

Affected Products

• Craws OpenAtlas v8.12.0
• OpenAtlas deployments used by the Austrian Archaeological Institute
• Any instance running the affected craws:openatlas component

Discovery Timeline

• 2025-11-24 - CVE-2025-56423 published to NVD
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-56423

Vulnerability Analysis

OpenAtlas v8.12.0 exposes a user enumeration weakness through its authentication endpoint. The login page returns different error messages depending on whether the submitted username exists in the database. An attacker submitting a valid username with an invalid password receives a response distinct from one indicating a non-existent account. This observable discrepancy converts the login form into an oracle for account validity.

The issue falls under CWE-203, which covers observable differences in application behavior that leak information about internal state. While the vulnerability itself does not grant access, it materially reduces the effort required to compromise accounts. Further technical detail is available in the Sec4You advisory.

Root Cause

The root cause is inconsistent error handling in the authentication flow. The application discloses account existence through response content rather than returning a uniform failure message for all invalid login attempts. Secure authentication design requires that responses to failed logins be indistinguishable regardless of whether the username, password, or both are incorrect.

Attack Vector

The attack requires no authentication and can be executed remotely over the network. An attacker automates login attempts with a list of candidate usernames and parses the response body, status code, or timing to determine which accounts exist. The enumerated list can then be used for password spraying, credential stuffing with breached password corpora, or targeted phishing.

No verified proof-of-concept code is published. The vulnerability is exploitable through standard HTTP tooling against the OpenAtlas login endpoint. Refer to the Sec4You vulnerability listing for additional context.

Detection Methods for CVE-2025-56423

Indicators of Compromise

• High volume of POST requests to the OpenAtlas login endpoint from a single source IP or distributed IP set within a short window
• Sequential or dictionary-ordered username submissions in web server access logs
• Login attempts with a large number of distinct usernames but few or no successful authentications
• User-Agent strings associated with automation tools such as curl, python-requests, or hydra

Detection Strategies

• Instrument the OpenAtlas login endpoint to log both the submitted username and the resulting response class, enabling statistical detection of enumeration patterns
• Correlate failed login events across time windows to identify sources testing many unique usernames
• Deploy web application firewall rules that rate-limit and alert on repeated authentication failures per source IP

Monitoring Recommendations

• Alert on any source generating more than a configurable threshold of failed login attempts with distinct usernames per minute
• Track baseline authentication failure rates and trigger investigation on statistical deviations
• Forward web server and application logs to a centralized SIEM for retention and cross-source correlation

How to Mitigate CVE-2025-56423

Immediate Actions Required

• Contact the OpenAtlas maintainers or monitor the project repository for a patched release beyond v8.12.0
• Place the OpenAtlas login endpoint behind a reverse proxy or WAF that enforces rate limiting and CAPTCHA challenges
• Enable multi-factor authentication for all OpenAtlas accounts to reduce the value of enumerated usernames
• Audit existing accounts and enforce strong password policies to blunt follow-on credential attacks

Patch Information

No vendor patch is referenced in the NVD entry at the time of publication. Administrators should track the OpenAtlas project for updates and apply any release addressing user enumeration in the authentication flow. Consult the Sec4You advisory for the latest disclosure status.

Workarounds

• Configure the reverse proxy or application layer to return a uniform generic error message for all failed login attempts, regardless of username validity
• Implement account lockout or progressive delay after repeated authentication failures from the same source
• Restrict access to the OpenAtlas administrative interface to trusted networks or VPN clients where operationally feasible
• Enable IP-based rate limiting on the login endpoint to slow automated enumeration to impractical rates

# Example nginx rate limit for the OpenAtlas login endpoint
http {
    limit_req_zone $binary_remote_addr zone=openatlas_login:10m rate=5r/m;

    server {
        location /login {
            limit_req zone=openatlas_login burst=3 nodelay;
            proxy_pass http://openatlas_backend;
        }
    }
}