CVE-2025-4440 is a critical buffer overflow vulnerability identified in the H3C GR-1800AX router, specifically affecting firmware versions up to 100R008. The vulnerability resides in the EnableIpv6 function within the /goform/aspForm component. An attacker with access to the local network can manipulate the argument parameter passed to this function, triggering a buffer overflow condition. This overflow can potentially allow the attacker to execute arbitrary code or cause a denial of service by corrupting memory. The vulnerability does not require user interaction but does require the attacker to have local network access and low privileges (PR:L), indicating that the attacker must be authenticated or have some level of access within the network. The CVSS 4.0 score is 8.6 (high severity), reflecting the significant impact on confidentiality, integrity, and availability, with low attack complexity and no user interaction needed. Although no public exploits are currently known in the wild, the vulnerability has been publicly disclosed, increasing the risk of exploitation. The lack of available patches at the time of disclosure further elevates the threat. The vulnerability's exploitation could compromise the router, potentially allowing attackers to intercept, modify, or disrupt network traffic, pivot within the network, or establish persistent access.

For European organizations, this vulnerability poses a substantial risk, especially for those relying on H3C GR-1800AX routers in their network infrastructure. Successful exploitation could lead to unauthorized control over network routing devices, enabling attackers to intercept sensitive communications, disrupt network availability, or launch further attacks within the internal network. This is particularly critical for sectors such as finance, healthcare, government, and critical infrastructure, where network integrity and confidentiality are paramount. The requirement for local network access somewhat limits remote exploitation but does not eliminate risk, as attackers could gain initial footholds through phishing or insider threats. Additionally, the public disclosure without an available patch increases the window of exposure. Organizations may face regulatory and compliance repercussions under GDPR if personal data confidentiality is compromised. The potential for lateral movement within networks also raises concerns about broader organizational impact beyond the initial device compromise.

European organizations should immediately inventory their network devices to identify any H3C GR-1800AX routers running affected firmware versions (up to 100R008). Until a vendor patch is available, organizations should implement strict network segmentation to isolate these devices from untrusted or less secure network segments, minimizing local network access to trusted administrators only. Employ network access controls such as 802.1X authentication and MAC address filtering to restrict device access. Monitor network traffic for unusual activity targeting the /goform/aspForm endpoint or suspicious parameter manipulation attempts. Deploy intrusion detection/prevention systems (IDS/IPS) with custom signatures to detect exploitation attempts. Regularly review and tighten router management interface access policies, disabling unnecessary services and enforcing strong authentication mechanisms. Engage with H3C for timely patch releases and apply updates as soon as they become available. Additionally, conduct internal security awareness training to reduce insider threat risks and ensure rapid incident response capabilities are in place to contain any exploitation.