CVE-2025-40773 Overview
CVE-2025-40773 is a broken access control vulnerability in Siemens SiPass integrated, an enterprise access control system. The flaw affects all versions prior to V3.0. The authorization mechanism lacks sufficient server-side checks on a specific API endpoint. An adjacent-network attacker with low privileges can invoke the endpoint and manipulate data belonging to other users. The weakness is classified as [CWE-639] Authorization Bypass Through User-Controlled Key, commonly known as an Insecure Direct Object Reference (IDOR).
Critical Impact
Authenticated attackers on an adjacent network can bypass authorization controls to read or modify records that belong to other SiPass integrated users.
Affected Products
- Siemens SiPass integrated (all versions before V3.0)
- Siemens SiPass integrated server applications exposing the affected API
- Deployments accessible from adjacent networks used by SiPass clients
Discovery Timeline
- 2025-10-14 - CVE-2025-40773 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-40773
Vulnerability Analysis
SiPass integrated exposes API endpoints that operate on user-owned records. The affected server application authenticates the caller but fails to verify that the caller owns or has permission to act on the referenced object. As a result, a low-privileged authenticated user can craft an API request referencing another user's identifier and perform actions against that user's data. The impact is limited to integrity of user-scoped data; confidentiality and availability are not directly affected according to the published CVSS metrics.
Root Cause
The root cause is missing server-side authorization enforcement on an API handler. The application relies on client-side or partial checks rather than validating the relationship between the authenticated principal and the requested resource on every request. This matches the pattern described by [CWE-639], where a user-controlled key in the request is trusted without cross-referencing session context.
Attack Vector
Exploitation requires network reachability to the SiPass integrated server from an adjacent network and valid low-privileged credentials. The attacker sends a specifically crafted API request substituting another user's object identifier. Because the server does not enforce ownership, the request succeeds and modifies data belonging to the victim account. No user interaction is required.
No public proof-of-concept or exploit code is available for CVE-2025-40773. See the Siemens Security Advisory SSA-599451 for vendor-supplied technical details.
Detection Methods for CVE-2025-40773
Indicators of Compromise
- Authenticated API requests from a single SiPass account referencing object identifiers associated with multiple other user accounts.
- Unexpected modifications to cardholder, credential, or access-permission records that do not correlate with normal operator activity.
- Audit log entries showing writes to records outside the acting operator's administrative scope.
Detection Strategies
- Enable and centralize SiPass integrated server audit logs, then correlate operator identity against the object identifiers touched by each request.
- Baseline normal per-operator API usage and alert on sudden increases in cross-user object references.
- Inspect network traffic between SiPass clients and servers for API calls containing enumerated or sequential identifiers.
Monitoring Recommendations
- Forward SiPass application and Windows event logs to a centralized SIEM for retention and correlation.
- Monitor privileged account creation, role changes, and permission grants inside SiPass integrated for out-of-band modifications.
- Alert on any SiPass integrated server still reporting a version earlier than V3.0.
How to Mitigate CVE-2025-40773
Immediate Actions Required
- Upgrade Siemens SiPass integrated to V3.0 or later on all server instances.
- Inventory all SiPass integrated deployments and confirm patched versions using Siemens' release documentation.
- Rotate credentials for SiPass operator accounts if unauthorized activity is suspected during the exposure window.
Patch Information
Siemens has released SiPass integrated V3.0, which addresses CVE-2025-40773. Refer to the Siemens Security Advisory SSA-599451 for update packages, fixed version details, and vendor-recommended deployment steps.
Workarounds
- Restrict network access to SiPass integrated servers to trusted management VLANs and known client hosts only.
- Apply the defense-in-depth guidance in Siemens' operational guidelines for access control systems, including segmentation and firewall rules.
- Limit the number of low-privileged SiPass operator accounts and review role assignments to reduce the population of potential attackers.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
