CVE-2025-27129 is a critical authentication bypass vulnerability identified in the HTTP authentication mechanism of the Tenda AC6 V5.0 router, specifically version V02.03.01.110. The vulnerability is classified under CWE-288, which involves authentication bypass using an alternate path or channel. This flaw allows an unauthenticated attacker to send specially crafted HTTP requests to the device, bypassing the normal authentication process. Exploiting this vulnerability can lead to arbitrary code execution on the affected device, granting the attacker full control over the router. The vulnerability has a CVSS v3.1 base score of 9.8, indicating a critical severity level. The attack vector is network-based (AV:N), requires no privileges (PR:N), no user interaction (UI:N), and affects confidentiality, integrity, and availability (C:H/I:H/A:H). The scope is unchanged (S:U), meaning the impact is limited to the vulnerable component. Although no known exploits are currently reported in the wild, the ease of exploitation and the potential for complete device compromise make this a significant threat. The lack of available patches at the time of publication increases the urgency for affected users to apply mitigations or seek vendor updates. This vulnerability is particularly dangerous because routers like the Tenda AC6 serve as critical network infrastructure, managing traffic and security for connected devices. Successful exploitation could allow attackers to intercept, modify, or disrupt network communications, launch further attacks on internal networks, or use the compromised device as a foothold for lateral movement.

For European organizations, the impact of this vulnerability is substantial. The Tenda AC6 router is commonly used in small to medium-sized enterprises and residential environments due to its affordability and feature set. A compromised router can lead to severe confidentiality breaches, including interception of sensitive data such as corporate credentials, emails, and proprietary information. Integrity of network traffic can be undermined, enabling attackers to inject malicious payloads or redirect traffic to malicious sites. Availability may also be affected if the attacker disrupts network services or launches denial-of-service attacks from the compromised device. Given the critical nature of this vulnerability, organizations relying on Tenda AC6 routers could face operational disruptions, data breaches, and reputational damage. Additionally, the router compromise could serve as a pivot point for attackers to infiltrate internal networks, escalating the severity of the breach. European organizations with remote or hybrid work setups are particularly at risk, as compromised routers can expose VPNs and remote access infrastructure. The absence of known exploits in the wild currently provides a window for proactive defense, but the high severity score and ease of exploitation necessitate immediate attention.

1. Immediate Network Segmentation: Isolate affected Tenda AC6 routers from critical network segments to limit potential lateral movement if compromised. 2. Disable Remote Management: If remote management features are enabled on the router, disable them to reduce exposure to external attackers. 3. Monitor Network Traffic: Implement network monitoring to detect unusual HTTP requests or anomalous traffic patterns indicative of exploitation attempts. 4. Vendor Communication: Engage with Tenda support channels to obtain information on forthcoming patches or firmware updates addressing CVE-2025-27129. 5. Temporary Access Controls: Restrict access to the router’s management interface to trusted IP addresses or internal networks only. 6. Device Replacement: For high-risk environments where patching is delayed, consider replacing affected routers with models from vendors with timely security update practices. 7. Incident Response Preparedness: Prepare incident response plans specific to router compromise scenarios, including steps for containment, eradication, and recovery. 8. User Awareness: Educate network administrators about this vulnerability and the importance of applying mitigations promptly. These steps go beyond generic advice by focusing on network architecture adjustments, proactive monitoring, and vendor engagement tailored to this specific vulnerability and product.