CVE-2025-55499 is a medium-severity buffer overflow vulnerability identified in the Tenda AC6 router firmware version V15.03.06.23_multi. The flaw exists in the fromSetSysTime function, specifically triggered via the ntpServer parameter. Buffer overflow vulnerabilities occur when input data exceeds the allocated buffer size, potentially overwriting adjacent memory and leading to unpredictable behavior, including code execution or crashes. In this case, the vulnerability is remotely exploitable over the network (AV:N) but requires high attack complexity (AC:H), meaning an attacker must craft a precise input to trigger the overflow. No privileges or user interaction are required (PR:N/UI:N), increasing the risk of exploitation. The impact primarily affects confidentiality (C:H), allowing potential unauthorized disclosure of sensitive information, with limited impact on integrity (I:L) and no impact on availability (A:N). The vulnerability is classified under CWE-120, which corresponds to classic buffer overflow errors. No known exploits are currently reported in the wild, and no patches have been linked yet. The affected product, Tenda AC6, is a consumer-grade Wi-Fi 6 router commonly used in home and small office environments. The vulnerability arises from improper input validation of the ntpServer parameter, which is used to set system time via NTP (Network Time Protocol). Exploiting this flaw could allow an attacker to leak sensitive data from memory or potentially execute arbitrary code, depending on the overflow's nature and surrounding code context. Given the high attack complexity, exploitation may require detailed knowledge of the firmware and precise payload crafting.

For European organizations, the impact of this vulnerability depends largely on the deployment scale of Tenda AC6 routers within their networks. While primarily a consumer device, small businesses and home offices may use these routers, especially in remote work scenarios. Exploitation could lead to unauthorized disclosure of sensitive information within the router's memory, potentially exposing network configuration details or credentials. This could facilitate further attacks such as network intrusion or man-in-the-middle attacks. The lack of impact on availability reduces the risk of denial-of-service conditions, but confidentiality breaches remain a concern. Since no known exploits exist yet, the immediate risk is moderate; however, the presence of a buffer overflow with remote network access and no authentication required means that motivated attackers could develop exploits. European organizations with remote employees using vulnerable routers could face increased risk, especially if these devices are not regularly updated or monitored. Additionally, the vulnerability could be leveraged as a foothold in supply chain or home network attacks, which have been increasingly targeted in Europe. The medium CVSS score reflects these considerations.

1. Immediate mitigation should include identifying and inventorying Tenda AC6 routers within the organization's environment, including remote and home office deployments. 2. Monitor vendor communications closely for official patches or firmware updates addressing this vulnerability and apply them promptly once available. 3. Until patches are released, restrict network access to router management interfaces, especially from untrusted networks, using firewall rules or VPNs. 4. Disable or restrict NTP configuration capabilities remotely if possible, or limit the ntpServer parameter input to trusted sources to reduce attack surface. 5. Implement network segmentation to isolate vulnerable devices from critical infrastructure and sensitive data. 6. Employ intrusion detection systems (IDS) or network monitoring tools to detect anomalous traffic patterns targeting NTP services or unusual packets directed at the router. 7. Educate remote users about the risks of using outdated router firmware and encourage regular updates and secure configuration practices. 8. Consider replacing vulnerable devices with models from vendors with stronger security track records if timely patching is not feasible.