CVE-2025-27917 is a remote denial of service vulnerability discovered in AnyDesk, a widely used remote desktop application, affecting versions through 9.0.4. The root cause is an incorrect deserialization process within the application that leads to failed memory allocation and a NULL pointer dereference. When an attacker sends specially crafted data to the AnyDesk service, this flaw triggers a crash of the application, resulting in denial of service by terminating active remote sessions or preventing new connections. The vulnerability does not require authentication or user interaction, making it remotely exploitable by any attacker able to reach the AnyDesk service endpoint. Although no public exploits have been reported yet, the nature of the flaw suggests it could be weaponized to disrupt remote support operations or teleworking environments. The absence of a CVSS score indicates this is a newly published vulnerability, with patches not yet available. The impact is primarily on availability, as confidentiality and integrity are not directly compromised. The vulnerability affects all deployments of vulnerable AnyDesk versions, regardless of platform, as the deserialization issue is inherent to the application’s core communication protocol. Organizations using AnyDesk for critical remote access should prioritize monitoring and prepare to deploy patches once released. Network segmentation and firewall rules restricting inbound access to AnyDesk services can reduce exposure. This vulnerability highlights the risks associated with deserialization flaws in remote access software, emphasizing the need for secure coding practices and timely patch management.

For European organizations, the primary impact of CVE-2025-27917 is the disruption of remote desktop services provided by AnyDesk, which is commonly used for IT support, remote work, and access to critical systems. A successful exploit can cause service outages, interrupting business continuity and potentially delaying critical operations. Sectors such as finance, healthcare, manufacturing, and government agencies that rely heavily on remote access tools may face operational downtime and increased support costs. The denial of service could also hinder incident response and system maintenance activities, increasing organizational risk. While the vulnerability does not expose sensitive data or allow unauthorized control, the loss of availability can have cascading effects, especially in environments with limited alternative remote access solutions. European organizations with remote work policies or third-party vendor access via AnyDesk are particularly vulnerable. The lack of authentication requirement for exploitation increases the attack surface, especially if AnyDesk services are exposed to untrusted networks. This could lead to targeted attacks against high-value entities or critical infrastructure within Europe, amplifying the potential impact.

1. Monitor AnyDesk vendor communications closely and apply security patches immediately upon release to remediate the deserialization flaw. 2. Restrict network access to AnyDesk services using firewall rules, VPNs, or zero-trust network access solutions to limit exposure to trusted users and networks only. 3. Implement network segmentation to isolate systems running AnyDesk from the broader enterprise network, reducing the blast radius of a potential DoS attack. 4. Employ intrusion detection and prevention systems (IDS/IPS) to detect anomalous or malformed traffic targeting AnyDesk services that could indicate exploitation attempts. 5. Review and harden AnyDesk configuration settings to disable unnecessary features and enforce strong authentication where possible, even though this vulnerability does not require authentication. 6. Maintain up-to-date asset inventories to quickly identify and remediate vulnerable AnyDesk installations. 7. Develop and test incident response plans that include scenarios for remote access service disruption to ensure rapid recovery and continuity. 8. Educate IT and security teams about the risks of deserialization vulnerabilities and the importance of secure software development lifecycle practices.