CVE-2026-4773 Overview
CVE-2026-4773 is an authentication bypass vulnerability in Magarsus Consulting Ltd. Co. IDM-MFA, a multi-factor authentication product. The flaw stems from improper validation of a specified input type [CWE-1287], allowing an attacker to circumvent MFA controls. The issue affects IDM-MFA versions from 2025.11.27 up to (but not including) 2026.03.10. Exploitation requires user interaction and can be delivered over the network without prior authentication. A successful attack yields high impact on confidentiality and integrity of protected accounts and systems.
Critical Impact
An unauthenticated attacker can bypass IDM-MFA authentication and gain access to protected resources when a targeted user performs a required interaction.
Affected Products
- Magarsus Consulting Ltd. Co. IDM-MFA 2025.11.27
- Magarsus Consulting Ltd. Co. IDM-MFA releases prior to 2026.03.10
- Deployments of IDM-MFA used as a multi-factor authentication gateway
Discovery Timeline
- 2026-07-22 - CVE-2026-4773 published to the National Vulnerability Database
- 2026-07-22 - Last updated in NVD database
Technical Details for CVE-2026-4773
Vulnerability Analysis
CVE-2026-4773 is an authentication bypass caused by improper validation of a specified type of input [CWE-1287]. IDM-MFA fails to enforce strict type checking on a value that governs the MFA verification flow. An attacker can supply an unexpected type or malformed value that the server accepts and processes as though the MFA step succeeded.
The vulnerability sits at the boundary between the primary credential check and the second-factor challenge. Because the flaw resides in the MFA layer itself, it defeats a control that many organizations rely on to compensate for weak or compromised passwords. Confidentiality and integrity impacts are high, while availability is not affected.
Exploitation requires user interaction, which points to a delivery vector such as a crafted authentication link, a malicious page, or a request the user must approve or click through. No privileges are required prior to exploitation.
Root Cause
The root cause is a missing or incorrect type check on input consumed by the authentication logic [CWE-1287]. When the server processes a value whose type differs from the expected schema, the comparison or verification routine returns a state that the application interprets as a successful factor.
Attack Vector
An attacker crafts a request or link that a legitimate user interacts with. The IDM-MFA endpoint receives the malformed input, accepts it during the MFA step, and issues a session or authorization token that bypasses the second factor. Because the attack traverses the network and does not require credentials, exposed IDM-MFA endpoints are directly reachable targets. Technical details are limited to the vendor coordination notice; see the Siber Güvenlik Notification TR-26-0607 for the advisory record.
Detection Methods for CVE-2026-4773
Indicators of Compromise
- Successful authentication events in IDM-MFA logs that lack a corresponding second-factor challenge/response pair.
- Authentication requests containing unexpected parameter types (arrays, objects, or null values) where scalars are expected.
- Session issuance to users from unusual geolocations or devices immediately after an MFA prompt was delivered but not confirmed by the user.
- Repeated authentication attempts against the same account followed by an unexpected success from a new client fingerprint.
Detection Strategies
- Enable verbose logging on the IDM-MFA authentication endpoints and forward events to a SIEM for correlation between primary-credential success and second-factor completion.
- Alert on any authentication flow where the MFA verification response contains malformed, non-scalar, or type-mismatched fields.
- Correlate IDM-MFA session issuance with downstream application logins to identify sessions that were never validated against a real second factor.
Monitoring Recommendations
- Baseline the ratio of MFA challenges issued to MFA challenges completed per user and alert on statistical deviations.
- Monitor for repeated 4xx responses from IDM-MFA endpoints followed by a 2xx success from the same source within a short window.
- Track user-agent and TLS-fingerprint changes between primary authentication and MFA completion for the same session.
How to Mitigate CVE-2026-4773
Immediate Actions Required
- Upgrade IDM-MFA to version 2026.03.10 or later on all deployments.
- Inventory every IDM-MFA instance, including test and disaster-recovery nodes, and confirm the running build.
- Invalidate active sessions and force reauthentication for users protected by IDM-MFA after patching.
- Review authentication and audit logs for the affected version window (2025.11.27 through builds prior to 2026.03.10) for signs of abuse.
Patch Information
Magarsus Consulting Ltd. Co. addressed the issue in IDM-MFA 2026.03.10. Administrators should apply the fixed release and validate that authentication flows now reject malformed input types. Consult the Siber Güvenlik Notification TR-26-0607 for the coordinated advisory reference.
Workarounds
- Restrict network exposure of IDM-MFA authentication endpoints to trusted networks or VPN clients until the patch is applied.
- Place a web application firewall in front of IDM-MFA and enforce strict JSON schema validation on authentication request bodies, rejecting non-scalar values where scalars are expected.
- Increase user awareness to reduce the likelihood of interaction with unsolicited authentication links, since exploitation requires user interaction.
- Temporarily require an additional out-of-band verification (for example, help-desk callback) for high-privilege account logins until patched.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
