CVE-2025-41010: Hiberus Sintra CORS Auth Bypass Flaw

CVE-2025-41010 Overview

CVE-2025-41010 is an incorrect Cross-Origin Resource Sharing (CORS) configuration vulnerability in Hiberus Sintra. The application accepts cross-origin requests from untrusted origins while Access-Control-Allow-Credentials is enabled. Attackers can craft malicious web pages that issue authenticated cross-domain requests against Sintra on behalf of a victim user. Successful exploitation can lead to unauthorized privileged actions and disclosure of confidential information. The weakness is classified under CWE-942: Permissive Cross-domain Policy with Untrusted Domains.

Critical Impact
An attacker can perform privileged actions and read confidential data from an authenticated user's session by luring the victim to a malicious origin.

Affected Products

Hiberus Sintra (vendor advisory does not enumerate specific fixed versions)

Discovery Timeline

2025-10-02 - CVE-2025-41010 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-41010

Vulnerability Analysis

The vulnerability stems from an overly permissive CORS policy in Hiberus Sintra. The server reflects or accepts arbitrary Origin header values in the Access-Control-Allow-Origin response header. It simultaneously returns Access-Control-Allow-Credentials: true, instructing browsers to include cookies and authentication headers in cross-origin responses.

Browsers rely on CORS response headers to determine whether a script running on origin A may read responses from origin B. When a server trusts untrusted origins and allows credentials, the browser's Same-Origin Policy protections are effectively neutralized for that endpoint. An attacker-controlled site can then read authenticated responses from the target application.

Exploitation requires user interaction: the victim must visit an attacker-controlled page while authenticated to Sintra. The attack executes over the network without requiring any privileges on the target application.

Root Cause

The root cause is a misconfigured CORS policy that fails to validate the Origin request header against an allowlist of trusted domains. Instead of rejecting unknown origins, the server echoes the requester's origin or uses a wildcard while asserting credential support. This combination is prohibited by the CORS specification for good reason: it exposes authenticated endpoints to any web page a victim visits.

Attack Vector

An attacker hosts a malicious page that issues fetch or XMLHttpRequest calls to Sintra with credentials: 'include'. When an authenticated victim loads the page, the browser attaches the user's session cookies. Sintra responds with permissive CORS headers, allowing the attacker's JavaScript to read the response body. The attacker can also invoke state-changing API endpoints to perform privileged actions on behalf of the victim.

See the INCIBE Security Notice for the coordinated disclosure details.

Detection Methods for CVE-2025-41010

Indicators of Compromise

HTTP responses from Sintra containing Access-Control-Allow-Origin values that mirror arbitrary Origin request headers alongside Access-Control-Allow-Credentials: true.
Cross-origin fetch or XMLHttpRequest calls to Sintra endpoints originating from unexpected referrers or third-party domains.
Spikes in authenticated API calls carrying Origin headers that do not match approved corporate domains.

Detection Strategies

Inspect web server and reverse proxy access logs for requests where the Origin header does not match the application's canonical domains, then correlate with authenticated session identifiers.
Use a web application scanner or a manual curl test that sends Origin: https://attacker.example and inspect whether the server reflects it while also returning Access-Control-Allow-Credentials: true.
Monitor browser telemetry and Content Security Policy (CSP) violation reports for anomalous cross-origin activity involving Sintra endpoints.

Monitoring Recommendations

Enable verbose logging of CORS preflight (OPTIONS) requests and the Origin header on the reverse proxy or WAF fronting Sintra.
Alert on authenticated API responses that carry both a reflected Access-Control-Allow-Origin and Access-Control-Allow-Credentials: true.
Continuously review outbound Referer telemetry from user endpoints to identify browsing sessions that pivot to Sintra from unapproved third-party sites.

How to Mitigate CVE-2025-41010

Immediate Actions Required

Contact Hiberus for the fixed version of Sintra and apply the vendor-supplied update as soon as it is available.
Restrict Access-Control-Allow-Origin to an explicit allowlist of trusted domains and never reflect arbitrary Origin values.
Disable Access-Control-Allow-Credentials on endpoints that do not require authenticated cross-origin access.
Enforce SameSite=Lax or SameSite=Strict on session cookies to reduce the impact of cross-origin credentialed requests.

Patch Information

Refer to the INCIBE Security Notice for Hiberus Sintra for coordinated disclosure details and vendor remediation guidance. No specific fixed version is enumerated in the NVD record; contact the vendor directly to confirm the patched release.

Workarounds

Front Sintra with a reverse proxy or WAF that strips permissive CORS headers and enforces an origin allowlist before responses reach the client.
Require anti-CSRF tokens on state-changing endpoints so that reflected CORS misconfiguration alone cannot authorize privileged actions.
Segment access to Sintra behind a VPN or zero-trust network access gateway to limit exposure to browser-initiated cross-origin attacks.

bash

# Example: strict CORS allowlist on an Nginx reverse proxy fronting Sintra
map $http_origin $cors_origin {
    default "";
    "https://sintra.example.com"        $http_origin;
    "https://admin.sintra.example.com"  $http_origin;
}

server {
    listen 443 ssl;
    server_name sintra.example.com;

    location / {
        if ($cors_origin = "") {
            return 403;
        }
        add_header Access-Control-Allow-Origin      $cors_origin always;
        add_header Access-Control-Allow-Credentials "true"       always;
        add_header Vary                             "Origin"     always;
        proxy_pass http://sintra_backend;
    }
}