Alert: NCSC issues advice following global targeting of Fortinet firewalls and VPN gateways
Published Sources: NCSC UK
What is affected, what to do
Organisations using Fortinet services are being urged to take action following a campaign affecting firewalls and VPN gateways. What has happened?
The available sources name no fixed version. Check the vendor guidance in the references below.
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
—
Priority
No value is available for this vulnerability.
—
CVSS v3
No value is available for this vulnerability.
—
EPSS score
No value is available for this vulnerability.
Show all metrics
- Severity
- Not rated
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 19.22 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Organisations using Fortinet services are being urged to take action following a campaign affecting firewalls and VPN gateways. What has happened? Fortinet firewalls and VPN gateways have been targeted as part of a global campaign, with some indications of potential impact in the UK. A database of credentials has been leaked by a threat actor following brute-force, dictionary and credential stuffing attempts against internet-facing FortiGate and VPN portals. Credential stuffing is a method where attackers use passwords stolen from one web service to try to access accounts on other services, taking advantage of any reuse of username and password combinations. Who is affected? Organisations using these products should prioritise investigating whether they have been affected and, as soon as possible, follow mitigation advice to help defend against the threat. Use one of the FortiBleed asset checkers for any domains that may have been affected: SOCRadar's FortiBleed Check Hudson Rock’s FortiBleed Checker What should I do? UK organisations using Fortinet edge devices with SSL VPN enabled should investigate potentially malicious activity on the device and monitor their network for unusual activity. Fortinet has published a blog post providing guidance and an analysis . The priority actions should be: Check SOCRadar's FortiBleed Checker or Hudson Rock’s FortiBleed Checker for any domains that are not listed in their Early Warning asset list. Confirm whether the device exists and belongs to you. Determine if your Fortinet device is compromised by looking for common Indicators of Compromise (IoC), including unauthorised account creation, and unexpected activity in log files. (See: Technical Tip: Collect Indicators of Compromise (IoC) ) If evidence of compromise exists, isolate the device from the internet and your internal network. If you believe you have been compromised, and are in the UK, you should report it and consider using an assured Cyber Incident Response provider . You can also report the compromise to the vendor to assist their investigation. Factory reset the device, as changing credentials alone may not be sufficient if threat actors have obtained persistence on the device (see: Technical Tip: How to reset to Factory Default configuration ). Ensure you have obtained logs, configs and other artefacts from the device useful for investigations which will be destroyed during the factory reset process. Investigate other edge devices that share credentials with the compromised device. Investigate devices reachable by the compromised device and monitor firewall logs for suspicious activity in order to obtain assurance that onward compromise within your network has not occurred. Harden the re-commissioned system including: Ensure management interfaces are not exposed to the internet. Update to the latest version. Remove out of support systems as soon as possible. Change all default, generic, or reused administrator passwords. Ensure multi-factor authentication (also known as 2-step verification) is enforced on all VPN and device management logins. Enable PBKDF2 for admin interface and enforce all admins re-login to the device (see: Technical Tip: Enforcing PBKDF2 as hash function for administrator accounts )