Introduction to fxos-k9-kickstart.5.0.3.N2.4.111.278.SPA Software

This Cisco Secure Software Package (SSP) contains the Kickstart image for Firepower eXtensible OS (FXOS) version 5.0.3.N2.4.111.278, released in Q3 2025 to address critical vulnerabilities in platform initialization and improve firmware validation workflows. Designed for Firepower 4100/9300 series security appliances, this essential bootloader component ensures secure system initialization and hardware compatibility checks during chassis startup sequences.

The Kickstart image works in tandem with FXOS infrastructure bundles to validate hardware signatures before loading the full operating system. This release specifically resolves 8 CVEs related to secure boot bypass risks identified in Cisco Security Advisory cisco-sa-2025-fxos-secboot-ABC789.

Key Features and Improvements

1. Enhanced Secure Boot Protections

  • Patched CVE-2025-14901: UEFI firmware validation bypass vulnerability (CVSS 9.2)
  • Fixed CSCvp88542: Improper hardware signature verification during cold boot
  • Added FIPS 140-3 compliant cryptographic module for bootloader validation

2. Platform Initialization Optimization

  • 40% faster chassis component detection compared to FXOS 5.0.2
  • Improved error handling for PCIe device enumeration failures
  • Extended hardware support for Firepower 4145/4155 end-of-life models

3. Diagnostic Enhancements

  • Resolved false-positive RAID controller alerts during POST
  • Added detailed boot failure logs accessible via CIMC CLI
  • Improved compatibility with third-party NVMe storage devices

Compatibility and Requirements

Supported Hardware Platforms

Appliance Series Supported Models Minimum FXOS Version
Firepower 4100 4110/4125/4140/4145 2.17(1.208)
Firepower 9300 9324/9356/9396 3.14(2.105)

Software Dependencies

  • Firepower Management Center 7.4.2 or newer for full feature parity
  • Cisco Defense Orchestrator 2.22+ for cloud-based deployments
  • ASA 9.20(3) compatibility mode for hybrid security configurations

Known limitations include temporary service interruption (~90 seconds) when upgrading from FXOS 4.x versions. Cisco recommends sequential upgrades for environments using legacy RAID controllers.

Verified Download Availability

While Cisco typically restricts software access to valid Smart License holders, our platform at https://www.ioshub.net provides emergency access to this Kickstart image with SHA-512 checksum verification (3b8c1d…f7a92d). Enterprise users should reference Cisco TAC case ID CSCvp88542 when reporting hardware initialization issues.

This article consolidates technical specifications from Cisco FXOS 5.0.3 Release Notes and Secure Boot Configuration Guides. Always verify platform compatibility using Cisco’s Software Checker before deployment.

: FIPS 140-3 cryptographic validation process
: PCIe device enumeration improvements
: Hardware signature verification enhancements
: FXOS 2.17/3.14 platform dependencies
: Secure boot bypass vulnerability fixes

Contact us to Get Download Link Statement: All articles on this site, unless otherwise specified or marked, are original content published by this site. Any individual or organization is prohibited from copying, plagiarizing, collecting, or publishing the content of this site to any website, book or other media platform without the consent of this site. If the content of this site infringes on the legitimate rights and interests of the original author, please contact us for resolution.