CVE-2024-26013: Fortinet FortiAnalyzer Auth Bypass Flaw

CVE-2024-26013 Overview

CVE-2024-26013 is an improper restriction of communication channel to intended endpoints vulnerability [CWE-923] affecting multiple Fortinet products. The flaw resides in the FortiGate-to-FortiManager (FGFM) authentication exchange between management devices and managed devices. An unauthenticated attacker in a man-in-the-middle position can intercept the FGFM authentication request and impersonate the management device, including the FortiCloud server and, under certain conditions, FortiManager itself. Affected products include FortiOS, FortiProxy, FortiManager, FortiAnalyzer, FortiVoice, and FortiWeb across multiple release branches.

Critical Impact
A successful attack allows an adversary positioned between a managed device and its management plane to impersonate FortiCloud or FortiManager, undermining device integrity and confidentiality of managed Fortinet infrastructure.

Affected Products

Fortinet FortiOS 7.4.0–7.4.4, 7.2.0–7.2.8, 7.0.0–7.0.15, 6.4.0–6.4.15, and versions before 6.2.16
Fortinet FortiProxy 7.4.0–7.4.2, 7.2.0–7.2.9, and versions before 7.0.15; Fortinet FortiManager 7.4.0–7.4.2, 7.2.0–7.2.4, 7.0.0–7.0.11, 6.4.0–6.4.14, and before 6.2.13
Fortinet FortiAnalyzer 7.4.0–7.4.2, 7.2.0–7.2.4, 7.0.0–7.0.11, 6.4.0–6.4.14, before 6.2.13; FortiVoice 7.0.0–7.0.2 before 6.4.8; FortiWeb before 7.4.2

Discovery Timeline

2025-04-08 - CVE-2024-26013 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-26013

Vulnerability Analysis

The vulnerability stems from insufficient validation of the communication channel between a managed Fortinet device and its upstream management endpoint. During the FGFM authentication request, the managed device does not adequately verify the identity of the FortiCloud server or, in specific conditions, the FortiManager. An attacker who can intercept network traffic between these endpoints can substitute their own endpoint and complete the authentication handshake.

The weakness is classified under [CWE-923] (Improper Restriction of Communication Channel to Intended Endpoints). Exploitation requires the attacker to occupy a man-in-the-middle position on the network path used by FGFM, and the attack complexity is high. Successful exploitation impacts confidentiality, integrity, and availability of the managed device because the management channel is implicitly trusted.

Root Cause

The root cause is improper endpoint validation in the FGFM protocol authentication flow. The managed device accepts FGFM authentication responses without sufficiently confirming that the responding peer is the legitimate FortiCloud or FortiManager instance. Trust anchoring on the management channel is incomplete, allowing impersonation.

Attack Vector

The attack vector is network-based and requires user interaction in the form of a triggering management exchange between the device and its management endpoint. An attacker must first gain a privileged network position between the managed device and the management plane. This can be achieved through compromised upstream infrastructure, rogue routing, DNS manipulation, or ARP poisoning on a shared segment. Once positioned, the attacker intercepts the FGFM authentication request and responds as the management device.

No public proof-of-concept exploit is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Refer to the FortiGuard Security Advisory FG-IR-24-046 for vendor technical details.

Detection Methods for CVE-2024-26013

Indicators of Compromise

Unexpected FGFM authentication attempts originating from IP addresses outside the documented FortiCloud or FortiManager address ranges.
Anomalous TLS certificate fingerprints or mismatched server identities presented during FGFM session establishment.
Configuration changes pushed to managed devices that do not correlate with administrative activity recorded on the legitimate FortiManager.

Detection Strategies

Inspect FGFM traffic flows for deviations from approved upstream management endpoints, including unexpected destination IPs or unusual session timing.
Correlate management-plane activity on FortiManager and FortiCloud audit logs against configuration deltas observed on managed FortiOS, FortiProxy, and FortiWeb devices.
Monitor ARP tables, BGP advertisements, and DNS responses on segments carrying FGFM traffic for signs of interception or redirection.

Monitoring Recommendations

Centralize Fortinet device logs and FGFM session telemetry into a SIEM or data lake for cross-device correlation and historical baselining.
Alert on FGFM session resets followed by configuration push events, which can indicate a successful impersonation followed by attacker-driven changes.
Track changes to administrative trust relationships and certificate stores on managed devices and trigger review on any unexpected modification.

How to Mitigate CVE-2024-26013

Immediate Actions Required

Upgrade affected Fortinet products to fixed releases as listed in the FortiGuard advisory FG-IR-24-046.
Inventory all FortiOS, FortiProxy, FortiManager, FortiAnalyzer, FortiVoice, and FortiWeb instances and prioritize remediation on devices managed via FGFM over untrusted networks.
Validate the integrity of recent configuration changes on managed devices and roll back any that cannot be attributed to authorized administrators.

Patch Information

Fortinet has issued fixed builds across the affected product families. Customers should consult the FortiGuard Security Advisory FG-IR-24-046 for the specific fixed versions corresponding to their product and branch, and apply them following Fortinet's upgrade guidance.

Workarounds

Restrict FGFM traffic to dedicated, trusted out-of-band management networks where man-in-the-middle positioning is not feasible.
Enforce strict IP allow-listing on managed devices so that FGFM connections are only accepted from known FortiCloud and FortiManager addresses.
Where supported, disable FGFM management on devices that do not require centralized management until patched builds can be deployed.

bash

# Example: restrict FGFM management access on a FortiGate to a trusted FortiManager IP
config system central-management
    set type fortimanager
    set fmg "<trusted-fortimanager-ip>"
    config server-list
        edit 1
            set server-type update rating
            set server-address <trusted-forticloud-ip>
        next
    end
end