CVE-2024-12838 Overview
CGFIDO from Changing Information Technology contains an authentication bypass vulnerability in its passwordless login mechanism. Remote attackers holding regular user privileges can send a crafted request to switch to the identity of any other user, including administrators. The flaw is tracked as CWE-302: Authentication Bypass by Assumed-Immutable Data and enables full account takeover across the deployment.
Critical Impact
Any authenticated low-privilege user can impersonate an administrator, resulting in full compromise of confidentiality, integrity, and availability.
Affected Products
- Changing Information Technology CGFIDO passwordless login product
- Deployments relying on CGFIDO for FIDO-based single sign-on
- Applications integrating the vulnerable CGFIDO authentication component
Discovery Timeline
- 2024-12-31 - CVE-2024-12838 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-12838
Vulnerability Analysis
The vulnerability resides in the passwordless login flow of CGFIDO. The mechanism relies on client-supplied data to determine which account should be authenticated after credential verification. Because the server trusts this data instead of binding the authentication assertion to the requesting user, an attacker can specify an arbitrary target account.
An authenticated user with regular privileges can craft a request that changes the effective identity to any other user in the system. This includes privileged accounts such as administrators. The result is a complete authorization bypass without additional user interaction.
Root Cause
The root cause is improper enforcement of identity binding during the passwordless login step, classified under CWE-302. The server treats a user-controlled identifier as an immutable trust value. It does not validate that the identifier matches the cryptographic assertion or the current session context.
Attack Vector
Exploitation occurs over the network and requires only low-level authenticated access. The attacker authenticates with a valid regular account, then submits a modified login request that substitutes a target username or user identifier. The server accepts the substitution and issues a session for the target identity. See the TW-CERT Advisory: Security Alert and the TW-CERT Advisory: Incident Report for vendor guidance.
Detection Methods for CVE-2024-12838
Indicators of Compromise
- Authentication events where the account that initiated the request differs from the account issued a session token
- Sudden administrator sessions originating from source IPs previously associated only with low-privilege users
- CGFIDO login requests containing user identifier parameters that do not match the authenticated principal
Detection Strategies
- Correlate CGFIDO authentication logs with application-level session logs to flag identity mismatches
- Alert on privilege elevation events where a user account transitions to administrator context without a documented role change
- Inspect HTTP request bodies to the passwordless login endpoint for tampered user identifier fields
Monitoring Recommendations
- Enable verbose logging on the CGFIDO authentication service and forward logs to a centralized SIEM
- Monitor for repeated failed and successful login attempts targeting administrative accounts
- Track anomalous session creation patterns, including short-lived sessions followed by privileged actions
How to Mitigate CVE-2024-12838
Immediate Actions Required
- Apply the vendor patch referenced in the TW-CERT Advisory: Security Alert as soon as it is available in your environment
- Restrict network access to the CGFIDO authentication endpoints to trusted networks until patching is complete
- Rotate credentials and invalidate active sessions for privileged accounts that use CGFIDO
Patch Information
Changing Information Technology has issued guidance through TW-CERT. Administrators should consult the TW-CERT Advisory: Incident Report for the fixed version and upgrade instructions specific to their deployment.
Workarounds
- Disable the passwordless login feature until the patched version is deployed
- Require multi-factor authentication for administrative accounts through an alternative authentication path
- Enforce strict server-side validation that binds the authenticated principal to the FIDO assertion before issuing sessions
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
