CVE-2023-41603 in R15
Summary
by MITRE • 01/10/2024
D-Link R15 before v1.08.02 was discovered to contain no firewall restrictions for IPv6 traffic. This allows attackers to arbitrarily access any services running on the device that may be inadvertently listening via IPv6.
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Analysis
by VulDB Data Team • 06/17/2025
The vulnerability identified as CVE-2023-41603 affects D-Link R15 routers running firmware versions prior to v1.08.02, presenting a critical security flaw in network traffic management. This issue stems from the absence of firewall restrictions specifically designed for IPv6 traffic within the device's security architecture, creating a significant attack surface that adversaries can exploit to gain unauthorized access to network services.
The technical flaw manifests as a complete lack of IPv6 packet filtering mechanisms within the router's firewall implementation. IPv6 traffic flows through the device without any inspection or restriction, allowing malicious actors to establish connections directly to services that may be running on the router or connected devices. This vulnerability represents a fundamental failure in network security design where the device assumes all IPv6 traffic is legitimate and trustworthy, effectively bypassing the traditional firewall controls that would normally protect against unauthorized access.
From an operational perspective, this vulnerability enables attackers to perform various malicious activities including port scanning, service enumeration, and direct exploitation of vulnerable services running on the affected device. The impact extends beyond simple network access as attackers can potentially leverage this weakness to establish persistent backdoors, conduct man-in-the-middle attacks, or use the router as a pivot point to access internal network resources. The vulnerability is particularly concerning because IPv6 is increasingly becoming the default protocol in modern networks, making this exposure more prevalent and dangerous.
The weakness aligns with CWE-1190, which addresses insufficient firewall restrictions for network traffic, and maps to ATT&CK technique T1046 for network service scanning and T1071.1003 for application layer protocol: DNS. Organizations using affected D-Link R15 devices should immediately implement mitigations including firmware updates to version 1.08.02 or later, manual firewall configuration to restrict IPv6 traffic, and network segmentation to limit the potential impact of such vulnerabilities. Additionally, network administrators should conduct thorough audits of all network devices to identify similar vulnerabilities and ensure proper IPv6 traffic filtering is implemented across all network infrastructure components. The vulnerability underscores the critical importance of maintaining up-to-date firmware and implementing comprehensive network security policies that address both IPv4 and IPv6 traffic management.