CVE-2025-46806 is a vulnerability classified under CWE-823, which involves the use of an out-of-range pointer offset in the sslh software before version 2.2.4. sslh is a protocol multiplexer that allows multiple protocols to share a single port, commonly used to multiplex SSH, HTTPS, OpenVPN, and other protocols on port 443. The vulnerability arises from improper pointer arithmetic or bounds checking, leading to the possibility of accessing memory outside the intended buffer boundaries. This can cause a denial of service (DoS) condition on affected systems, particularly on certain architectures where memory layout or pointer handling is more sensitive to such errors. The vulnerability does not require authentication, user interaction, or privileges to exploit, and can be triggered remotely by sending crafted network traffic to the sslh service. The CVSS v4.0 base score is 6.9, indicating a medium severity level, with network attack vector, low attack complexity, no privileges or user interaction required, and a limited impact on availability (denial of service). No known exploits are currently reported in the wild, and no patch links are provided in the source data, but version 2.2.4 of sslh is indicated as the fixed version. The vulnerability affects all versions prior to 2.2.4, though exact affected versions are unspecified. The root cause is a pointer offset calculation error that leads to out-of-bounds memory access, which can crash the sslh process and disrupt service availability.

For European organizations, the primary impact of CVE-2025-46806 is the potential for denial of service attacks against systems running vulnerable versions of sslh. Since sslh is often deployed in environments where multiple protocols are multiplexed on a single port (commonly port 443), disruption can affect critical services such as SSH access, HTTPS web services, or VPN connections. This could lead to temporary loss of remote administrative access or interruption of secure communications, impacting business continuity and operational security. Organizations relying on sslh in perimeter or internal network gateways may experience service outages, which could be exploited as part of a broader attack strategy or to cause operational disruption. The vulnerability does not directly compromise confidentiality or integrity but can degrade availability, which is critical for many European enterprises, especially those in finance, healthcare, and critical infrastructure sectors. The lack of authentication or user interaction requirements increases the risk of automated exploitation attempts, although no exploits are currently known. The impact is more pronounced in environments with high reliance on sslh for protocol multiplexing and where rapid recovery from service disruption is challenging.

European organizations should prioritize upgrading sslh to version 2.2.4 or later, where the vulnerability is addressed. In the absence of an immediate upgrade path, organizations can implement network-level mitigations such as filtering or rate limiting incoming traffic to the sslh service to reduce exposure to crafted packets that trigger the out-of-range pointer offset. Monitoring sslh service logs and network traffic for anomalies or crashes can help detect attempted exploitation. Employing redundancy and failover mechanisms for services behind sslh can minimize operational impact during potential DoS events. Additionally, organizations should review their use of sslh and consider alternative multiplexing solutions with a stronger security track record if timely patching is not feasible. Regular vulnerability scanning and asset inventory updates should include sslh to ensure timely detection of vulnerable instances. Finally, coordinating with upstream vendors or open-source maintainers for patches and advisories is recommended to stay informed about any emerging exploits or fixes.