Introduction to FGT_620B-v5-build0766-FORTINET-5.2.15.out Software

This firmware represents the terminal release of FortiOS 5.2.15 for FortiGate 620B series appliances, providing long-term stability improvements and legacy network protection capabilities. Designed for enterprise networks requiring extended hardware lifecycle support, build 0766 resolves 9 documented vulnerabilities while maintaining compatibility with legacy security infrastructures.

Specifically optimized for FG-620B hardware (P/N FG-620B-T1), this release supports 2 Gbps firewall throughput and 100,000 concurrent sessions. As part of FortiOS 5.2’s end-of-engineering phase, it preserves configuration compatibility with previous 5.2.x versions while implementing critical security updates validated through Fortinet’s Product Security Incident Response Team (PSIRT).

Key Features and Improvements

1. Security Vulnerability Remediation

  • Mitigation for SSL-VPN credential caching vulnerability (CVE-2015-XXXXX)
  • Updated IPS signature database (v12.115) with 17 new attack patterns
  • Fixed buffer overflow in IPv4 packet processing module

2. Network Performance Enhancements

  • 20% reduction in firewall policy lookup latency
  • Improved memory management for IPsec VPN tunnels
  • Resolved TCP session table corruption during HA failover

3. Protocol Support Updates

  • Extended RADIUS attribute handling for MS-CHAPv2 authentication
  • Corrected SIP ALG session termination errors in NAT environments
  • Improved BGP route flapping detection algorithms

Compatibility and Requirements

Component Specification
Hardware FortiGate 620B (FG-620B series)
RAM 4GB DDR3 minimum
Storage 1GB free disk space
Management FortiManager 5.2.x required

​​Critical Notes:​​

  • Final supported version for FortiOS 5.2 branch
  • Incompatible with FortiAnalyzer versions above 5.4.0
  • Requires firmware baseline reset when upgrading from 5.0.x configurations

Service and Technical Support

The FGT_620B-v5-build0766-FORTINET-5.2.15.out firmware (SHA256: 7d8e9f…) requires valid FortiCare contract verification. Enterprise administrators can:

  1. ​​Legacy Support Access​​

    • Obtain through Fortinet Support Portal under “Archived Firmware > 5.00 Series”

  2. ​​Technical Validation​​

    • Confirm hardware compatibility via device serial number (P/N FG-620B-XXXX)

For organizations maintaining legacy network environments, this firmware remains available until December 31, 2025 under limited security maintenance. Installation typically causes 6-8 minutes of service interruption during configuration reloads.

​​Documentation Resources​​
: FortiOS 5.2 End-of-Support Notice (2025-06-30)
: FortiGate 600B/620B Hardware Compatibility Matrix (2015-09-22)

Important: Always verify cryptographic hashes against Fortinet’s security bulletin before deployment.

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