CVE-2026-23708: Fortinet FortiSOAR Auth Bypass Vulnerability

CVE-2026-23708 Overview

CVE-2026-23708 is an improper authentication vulnerability (CWE-287) affecting Fortinet FortiSOAR that allows unauthenticated attackers to bypass two-factor authentication (2FA) through replay attacks. The vulnerability exists in both FortiSOAR PaaS and on-premise deployments, enabling attackers who can intercept and decrypt authentication traffic to replay captured 2FA requests and gain unauthorized access to the security orchestration platform.

Critical Impact

Successful exploitation allows complete authentication bypass, potentially granting attackers full access to FortiSOAR's security orchestration, automation, and response capabilities, which could compromise an organization's entire security operations infrastructure.

Affected Products

• FortiSOAR PaaS 7.6.0 through 7.6.3
• FortiSOAR PaaS 7.5.0 through 7.5.2
• FortiSOAR on-premise 7.6.0 through 7.6.3
• FortiSOAR on-premise 7.5.0 through 7.5.2

Discovery Timeline

• 2026-04-14 - CVE CVE-2026-23708 published to NVD
• 2026-04-14 - Last updated in NVD database

Technical Details for CVE-2026-23708

Vulnerability Analysis

This authentication bypass vulnerability stems from improper handling of 2FA token validation in Fortinet FortiSOAR. The flaw allows attackers to capture legitimate 2FA authentication requests and replay them before the token expires, effectively circumventing the multi-factor authentication mechanism designed to protect the platform.

FortiSOAR serves as a security orchestration, automation, and response (SOAR) platform, making this vulnerability particularly concerning. Compromising such a system could give attackers visibility into an organization's security playbooks, incident response procedures, and potentially allow manipulation of automated security responses.

The attack requires the adversary to position themselves in a man-in-the-middle scenario where they can intercept and decrypt authentication traffic. Additionally, the replay must occur with precise timing before the 2FA token expires, which introduces complexity to successful exploitation. However, once these conditions are met, the authentication can be completely bypassed.

Root Cause

The root cause of CVE-2026-23708 lies in insufficient validation mechanisms for 2FA authentication requests. The system fails to properly implement anti-replay protections such as nonces, timestamps, or one-time-use token validation. This allows previously captured valid authentication requests to be accepted multiple times within the token's validity window, defeating the purpose of the second authentication factor.

Attack Vector

The attack vector is network-based and requires the following conditions:

1. Traffic Interception: The attacker must be able to intercept network traffic between the legitimate user and the FortiSOAR server. This could be achieved through network position compromise, ARP spoofing, DNS hijacking, or compromised network infrastructure.

2. Traffic Decryption: The attacker needs the ability to decrypt the captured authentication traffic, suggesting either a weakness in the transport layer security configuration or a compromised TLS implementation.

3. Timing Precision: The replay must occur before the 2FA token expires, requiring the attacker to act quickly after capturing the authentication request.

The vulnerability mechanism involves capturing a valid 2FA authentication request during a legitimate user's login attempt, then replaying that exact request to the server to authenticate as the targeted user without knowledge of their credentials.

For detailed technical information about this vulnerability and official remediation guidance, refer to the Fortinet PSIRT Advisory FG-IR-26-101.

Detection Methods for CVE-2026-23708

Indicators of Compromise

• Multiple successful authentication events from different source IP addresses using the same session or token identifiers within a short time window
• Authentication attempts originating from unusual geographic locations or IP ranges not consistent with normal user behavior
• Duplicate 2FA authentication requests with identical parameters occurring within milliseconds of each other
• Anomalous network traffic patterns suggesting man-in-the-middle positioning or traffic interception

Detection Strategies

• Implement monitoring for duplicate authentication request patterns that may indicate replay attacks
• Deploy network detection rules to identify potential traffic interception or ARP spoofing attempts
• Configure FortiSOAR audit logging to capture detailed authentication metadata including source IPs, timestamps, and token identifiers
• Establish baseline authentication patterns for users and alert on deviations that may suggest credential misuse

Monitoring Recommendations

• Enable verbose authentication logging within FortiSOAR to capture all 2FA-related events
• Monitor for concurrent sessions from the same user account originating from different source addresses
• Implement real-time alerting for authentication anomalies through your SIEM platform
• Review network traffic logs for signs of TLS interception or certificate anomalies

How to Mitigate CVE-2026-23708

Immediate Actions Required

• Upgrade affected FortiSOAR installations to the latest patched version as specified in Fortinet's security advisory
• Audit all FortiSOAR access logs for signs of unauthorized access or authentication anomalies
• Enforce strong network segmentation to limit potential man-in-the-middle attack surfaces
• Implement additional network-layer authentication controls such as certificate-based mutual TLS

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations should consult the Fortinet PSIRT Advisory FG-IR-26-101 for specific patch versions and upgrade instructions.

Verify your current FortiSOAR version and compare against the affected version ranges:

• PaaS: Versions 7.5.0 - 7.5.2 and 7.6.0 - 7.6.3 are vulnerable
• On-premise: Versions 7.5.0 - 7.5.2 and 7.6.0 - 7.6.3 are vulnerable

Workarounds

• Implement network access controls to restrict FortiSOAR management interface access to trusted networks only
• Deploy additional network monitoring to detect potential traffic interception attempts
• Enforce strict TLS configurations including certificate pinning where possible to prevent traffic decryption
• Consider implementing additional authentication layers or IP-based access restrictions until patches can be applied

Network segmentation configuration to limit FortiSOAR exposure:

# Configuration example
# Restrict FortiSOAR management access to trusted admin networks only
# Example firewall rules (syntax varies by platform)

# Allow HTTPS access only from trusted admin subnet
iptables -A INPUT -p tcp --dport 443 -s 10.0.100.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP

# Log all authentication attempts for audit purposes
# Enable detailed logging in FortiSOAR administration settings