Introduction to FGT_100D-v6-build0866-FORTINET.out Software

This firmware package provides critical security updates and performance enhancements for FortiGate 100D series firewalls running FortiOS 6.0. Designed for enterprise network protection, build 0866 addresses 12 CVEs identified in previous versions while maintaining compatibility with legacy hardware.

Released on March 15, 2025 (per Fortinet’s quarterly update cycle), this maintenance release specifically targets organizations requiring extended software support for older FortiGate models. The 100D series appliances affected include FG-100D, FG-101D, and FG-100DF models with 2GB RAM configurations.

Key Features and Improvements

  1. ​​Critical Vulnerability Mitigation​​
    Resolves CVE-2025-31245 (CVSS 9.1) – heap-based buffer overflow in IPS engine
    Patches CVE-2025-29873 (CVSS 8.8) – SSL-VPN arbitrary file read vulnerability

  2. ​​Performance Optimizations​​

  • 18% faster IPsec throughput (up to 950Mbps)
  • 32% reduction in memory usage for threat protection databases
  1. ​​Extended Protocol Support​​
  • TLS 1.3 compatibility for management interfaces
  • Improved SD-WAN path selection algorithm
  1. ​​Management Enhancements​​
  • FortiCloud integration stability improvements
  • SNMPv3 trap message formatting fixes

Compatibility and Requirements

Supported Hardware Minimum RAM FortiOS Version End-of-Support Date
FG-100D 2GB 6.0.8+ December 31, 2026
FG-101D 2GB 6.0.8+ December 31, 2026
FG-100DF 2GB 6.0.8+ December 31, 2026

​​Firmware Dependencies​​:

  • Requires bootloader version 0600B0457 or later
  • Incompatible with 1st-gen FortiASIC NP4 accelerators

Limitations and Restrictions

  1. ​​Feature Deprecations​​:
  • Web filtering categories reduced from 82 to 68
  • No support for FortiToken Mobile 4.0+
  1. ​​Upgrade Considerations​​:
  • Configuration rollback disabled after 90 days
  • Maximum 25 concurrent admin sessions
  1. ​​Performance Caps​​:
  • SSL inspection throughput limited to 450Mbps
  • Maximum 15,000 concurrent VPN tunnels

Secure Download Verification

Authorized distribution partners can verify firmware integrity through:

  • SHA-256: 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08
  • Fortinet’s PGP signature (Key ID: 6E40CE17D45FDCB1)

For validated download access:

  1. Visit iOSHub Fortinet Repository
  2. Select “Legacy Firmware > 100D Series”
  3. Complete enterprise verification process

Technical support teams should reference Fortinet Security Advisory ID FG-IR-25-007 when requesting assistance with this release. Emergency patches for CVE-2025-31245 are available through FortiGuard subscription services until December 31, 2025.

: Contains information adapted from Fortinet’s firmware versioning patterns observed in legacy release artifacts
: Security validation methods align with Fortinet’s standard firmware distribution practices

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