F5 Network Compromise: What UK Organisations Need to Know

October 15, 2025

The National Cyber Security Centre (NCSC) has issued urgent guidance following confirmation of a significant security incident affecting F5 Networks. Organisations across the UK using F5 products should take immediate action to protect their infrastructure.

Understanding the Breach

F5 Networks has confirmed a compromise of its internal systems, resulting in the theft of sensitive data including portions of BIG-IP source code and vulnerability information. This breach presents a serious concern for organisations relying on F5 infrastructure.

The stolen information could enable threat actors to:

  • Identify and exploit vulnerabilities in F5 devices and software
  • Conduct detailed analysis to discover logical flaws and security weaknesses
  • Develop highly targeted exploits specific to F5 products

If successfully exploited, attackers could potentially access embedded credentials and API keys, move laterally across your network, steal sensitive data, and establish long-term persistent access to your systems.

Whilst there's currently no evidence that customer networks have been directly compromised through this incident, the threat potential is significant enough to warrant immediate attention.


Which Products Are Affected?

The incident impacts a wide range of F5 products, including:

Hardware:

  • BIG-IP iSeries
  • BIG-IP rSeries
  • Any F5 device that has reached end of support

Software:

  • All devices running BIG-IP (F5OS)
  • BIG-IP (TMOS)
  • Virtual Edition (VE)
  • BIG-IP Next
  • BIG-IQ
  • BIG-IP Next for Kubernetes (BNK) / Cloud-Native Network Functions (CNF)


Seven Priority Actions for Your Organisation

If you use F5 products in your infrastructure, the NCSC recommends taking the following steps immediately:

1. Complete Asset Discovery

Conduct a comprehensive audit to identify all F5 products across your estate—hardware, software, and virtualised instances. You cannot protect what you don't know you have.

2. Secure Management Interfaces

Management interfaces should never be exposed to the internet. If you discover any internet-facing management interfaces, treat this as a potential security incident and conduct a thorough compromise assessment immediately.

3. Report Suspected Compromises

If you believe your systems have been compromised, contact F5's Security Incident Response Team (SIRT) without delay. UK organisations should also report incidents to the NCSC through the appropriate channels.

4. Implement Vendor Hardening Guidelines

Review and implement F5's best practice guidance for hardening your systems. These security measures can significantly reduce your attack surface and make exploitation more difficult.

5. Apply Security Updates

Install the latest F5 security updates across all affected products. Maintaining current patch levels is one of the most effective defences against exploitation.

6. Address End-of-Life Products

Replace any F5 products that have reached end of support. If immediate replacement isn't feasible, follow the NCSC's guidance on managing obsolete products to mitigate risks.

7. Enhance Monitoring and Threat Hunting

Implement continuous network monitoring and proactive threat hunting activities to detect any suspicious behaviour that might indicate attempted or successful exploitation.


The Broader Context

This incident serves as a reminder that even security infrastructure providers are not immune to sophisticated attacks. When a vendor's systems are compromised, the implications cascade across their entire customer base.

Whilst nginx products appear unaffected at present, organisations should still ensure these instances are updated to the latest versions, in line with the NCSC's vulnerability management guidance.


Taking a Proactive Stance

The window for action is now. Threat actors will be working to weaponise the stolen information, and organisations using F5 products must assume they are potential targets.

Don't wait for evidence of compromise before taking action. The steps outlined by the NCSC represent essential hygiene for any organisation operating F5 infrastructure. Beyond addressing this immediate threat, they also strengthen your overall security posture against future incidents.

If you require assistance assessing your exposure or implementing these security measures, consider engaging specialist support to ensure your response is both swift and comprehensive.

The cyber threat landscape continues to evolve, and incidents like this underscore the importance of maintaining robust security practices, keeping systems up to date, and having clear incident response procedures in place.


Need Expert Support?

If you're concerned about your exposure to this threat or need assistance implementing these critical security measures, Altiatech can help. Our cybersecurity specialists can assist with:

  • Comprehensive infrastructure assessments to identify all affected F5 products
  • Security hardening and configuration reviews
  • Compromise assessments if internet-facing management interfaces are discovered
  • Implementation of security updates and patches
  • Continuous monitoring and threat detection solutions

Get in touch with our team:

📧 Email: innovate@altiatech.com
📞 Phone (UK):
+44 (0)330 332 5482

Don't leave your infrastructure vulnerable. Contact us today to ensure your organisation is protected against this evolving threat.

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