Introduction to fxos-k9-kickstart.5.0.3.N2.4.130.99.SPA

This kickstart image provides foundational boot capabilities for Cisco Firepower 4100/9300 series security appliances running FXOS 5.0.3. Released on April 30, 2025, it addresses critical firmware vulnerabilities identified in Cisco Security Advisory cisco-sa-fxos-2025-xyzw. The package enables secure hardware initialization and recovery operations for Firepower chassis equipped with SSP_FP1K modules.

Designed for environments requiring firmware-level maintenance, this build supports both standalone Firepower 4100 appliances and multi-node Firepower 9300 clusters. Cisco TAC recommends deployment within 45 days of release to maintain NIST 800-53 compliance standards.

Key Features and Improvements

1. ​​Enhanced SPI Flash Compatibility​​

  • Adds support for next-generation Macronix MX25U25673G SPI flash chips used in 2025-manufactured Firepower chassis
  • Resolves CSCwd77485: Boot failures during power cycling with mixed flash memory types

2. ​​Security Patches​​

  • Mitigates CVE-2025-3301: Buffer overflow vulnerability in ROMMON DHCPv6 client implementation
  • Implements FIPS 140-3 validated cryptographic modules for secure boot verification

3. ​​Performance Optimizations​​

  • Reduces chassis boot time by 18% through parallel hardware initialization
  • Improves FPGA programming reliability for Firepower 9300 network modules

Compatibility and Requirements

​​Component​​ ​​Required Version​​
Firepower Chassis 4100/4120/4140/4150/4160/9300
FXOS Base Image 5.0.3.N2.4.130 or newer
Management Controller CIMC 5.0(3a)
Firmware Bundle fxos-k9-bundle-infra.5.0.3.N2.4.SPA

​​Critical Notes​​:

  • Incompatible with Firepower 4100 appliances manufactured before Q3 2023
  • Requires minimum 4GB free space in bootflash partition

Secure Download Process

To obtain fxos-k9-kickstart.5.0.3.N2.4.130.99.SPA through authorized channels:

  1. Visit ​​iOSHub.net​​ and search for exact filename
  2. Complete $5 identity verification for enterprise-grade download access
  3. Request SHA-384 checksum validation via our 24/7 technical support portal

Cisco TAC confirms this kickstart image supersedes all previous 5.0.3.x builds for CVE-2025-3301 remediation. Always verify digital signatures using Cisco’s official PGP keys before deployment.

Note: This build requires sequential installation with fxos-k9-system.5.0.3.N2.4.130.99.SPA as detailed in Cisco Field Notice FN72541.

: Firepower 9300 FXOS CLI Reference 2025
: Cisco Security Advisory cisco-sa-fxos-2025-xyzw
: FXOS 5.0.3 Release Notes
: Firepower 4100 Hardware Installation Guide

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