EUVD-2025-5925

Comprehensive Technical Analysis of EUVD-2025-5925

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-5925 is a stack-based buffer overflow in the URL parsing functionality of the TR069 STUN server. This flaw arises from insufficient bounds checking on the amount of URL parameters, allowing an attacker to exploit the overflow by sending a maliciously crafted request. The severity of this vulnerability is rated at a base score of 9.8 using CVSS 3.1, indicating a critical risk. The vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H highlights the following characteristics:

• Attack Vector (AV): Network (N) - The vulnerability is exploitable over the network.
• Attack Complexity (AC): Low (L) - The attack requires minimal skill or resources.
• Privileges Required (PR): None (N) - No privileges are required to exploit the vulnerability.
• User Interaction (UI): None (N) - No user interaction is required.
• Scope (S): Unchanged (U) - The vulnerability does not change the security scope.
• Confidentiality (C): High (H) - The vulnerability allows for unauthorized access to sensitive information.
• Integrity (I): High (H) - The vulnerability allows for unauthorized modification of data.
• Availability (A): High (H) - The vulnerability allows for disruption of service.

2. Potential Attack Vectors and Exploitation Methods

The primary attack vector is through network-based exploitation. An attacker can send a specially crafted request to the TR069 STUN server, which processes the request and triggers the stack-based buffer overflow. This can lead to arbitrary code execution with elevated privileges. Potential exploitation methods include:

• Remote Code Execution (RCE): By sending a maliciously crafted URL, an attacker can execute arbitrary code on the affected device.
• Denial of Service (DoS): The buffer overflow can cause the device to crash or become unresponsive, leading to a denial of service.
• Privilege Escalation: The attacker can gain elevated privileges, allowing them to perform unauthorized actions on the device.

3. Affected Systems and Software Versions

The vulnerability affects multiple models and versions of DrayTek Vigor routers:

• Vigor165/166: 4.2.7 and earlier
• Vigor2620/LTE200: 3.9.8.9 and earlier
• Vigor2860/2925: 3.9.8 and earlier
• Vigor2862/2926: 3.9.9.5 and earlier
• Vigor2133/2762/2832: 3.9.9 and earlier
• Vigor2135/2765/2766: 4.4.5 and earlier
• Vigor2865/2866/2927: 4.4.5.3 and earlier
• Vigor2962: 4.3.2.8 and earlier
• Vigor3912: 4.3.6.1 and earlier
• Vigor3910: 4.4.3.1 and earlier

4. Recommended Mitigation Strategies

To mitigate the risk associated with this vulnerability, the following strategies are recommended:

• Patch Management: Ensure that all affected devices are updated to the latest firmware versions that address this vulnerability.
• Network Segmentation: Implement network segmentation to isolate critical systems and reduce the attack surface.
• Firewall Rules: Configure firewalls to restrict access to the TR069 STUN server, allowing only trusted sources.
• Intrusion Detection Systems (IDS): Deploy IDS to monitor network traffic for suspicious activity and potential exploitation attempts.
• Regular Audits: Conduct regular security audits and vulnerability assessments to identify and address potential security weaknesses.

5. Impact on European Cybersecurity Landscape

The vulnerability poses a significant risk to the European cybersecurity landscape, particularly for organizations and individuals using DrayTek Vigor routers. The potential for remote code execution and denial of service can lead to data breaches, service disruptions, and unauthorized access to sensitive information. This underscores the importance of timely patching and robust security measures to protect against such threats.

6. Technical Details for Security Professionals

For security professionals, the following technical details are pertinent:

• Vulnerability Type: Stack-based buffer overflow
• Affected Component: URL parsing functionality of the TR069 STUN server
• Root Cause: Insufficient bounds checking on URL parameters
• Exploitation Method: Sending a maliciously crafted URL request
• Impact: Arbitrary code execution, denial of service, privilege escalation
• Mitigation: Apply firmware updates, implement network segmentation, configure firewalls, deploy IDS, conduct regular audits

Conclusion

EUVD-2025-5925 highlights a critical vulnerability in DrayTek Vigor routers that can be exploited for remote code execution and denial of service. Organizations and individuals using these devices should prioritize applying the necessary firmware updates and implementing robust security measures to mitigate the risk. The European cybersecurity landscape must remain vigilant against such threats to ensure the protection of sensitive information and the continuity of services.