CVE-2025-1566 is a high-severity vulnerability affecting the Native System VPN implementation in Google ChromeOS, specifically version 16002.23.0 on the Dev Channel. The vulnerability arises from a DNS leak caused by improper handling of DNS traffic during VPN state transitions. When the VPN connection changes state—such as connecting, disconnecting, or reconnecting—the system fails to properly tunnel DNS queries through the VPN. Instead, these DNS queries are exposed in plaintext to network observers. This leakage undermines the confidentiality of user DNS requests, potentially allowing attackers or network adversaries to monitor which domains users are querying, thereby compromising privacy and enabling further targeted attacks or surveillance. The vulnerability is categorized under CWE-1319, which relates to improper handling of network traffic leading to information exposure. The CVSS v3.1 base score is 7.5, indicating a high severity level, with the vector indicating network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but high impact on availability (A:H). However, the description suggests the primary risk is information exposure via DNS leakage rather than availability impact, which may indicate some discrepancy in the CVSS vector or a focus on denial of service aspects during VPN transitions. No known exploits are currently reported in the wild, and no patches are linked yet, indicating that mitigation may require updates from Google. This vulnerability specifically affects ChromeOS users running the specified Dev Channel version, which is often used by developers and early adopters. The DNS leak can be exploited by passive network observers, such as those on the same network segment or ISP-level adversaries, to monitor user activity despite VPN use, undermining the privacy guarantees expected from VPNs on ChromeOS devices.

For European organizations, this vulnerability poses a significant privacy risk, especially for entities relying on ChromeOS devices with Native System VPN for secure communications. The DNS leak can expose sensitive domain queries to network adversaries, potentially revealing internal or confidential browsing activities. This is particularly critical for organizations handling sensitive data, such as financial institutions, healthcare providers, and government agencies, where DNS query patterns could reveal operational details or user behavior. The exposure could facilitate targeted phishing, surveillance, or data exfiltration attempts. Additionally, since the vulnerability does not require user interaction or privileges, it can be exploited silently, increasing the risk of unnoticed data leakage. The impact on availability indicated by the CVSS score suggests potential VPN disruptions during state transitions, which could degrade user experience and trust in ChromeOS VPN solutions. Given the increasing adoption of ChromeOS in educational and enterprise environments across Europe, the vulnerability could affect a broad user base, undermining organizational security postures and compliance with data protection regulations such as GDPR.

To mitigate this vulnerability, European organizations should: 1) Immediately assess the deployment of ChromeOS devices, particularly those running the affected Dev Channel version 16002.23.0, and restrict usage to stable or beta channels where this vulnerability is not present. 2) Disable the Native System VPN feature temporarily if feasible, or use alternative VPN clients that do not exhibit this DNS leak behavior until a patch is released. 3) Employ DNS-over-HTTPS (DoH) or DNS-over-TLS (DoT) configurations where possible to encrypt DNS queries independently of the VPN tunnel, reducing the risk of plaintext exposure. 4) Monitor network traffic for unusual DNS query patterns or unexpected plaintext DNS requests originating from ChromeOS devices. 5) Educate users about the risks of using Dev Channel builds in production environments and enforce policies to limit such usage. 6) Stay updated with Google’s security advisories and apply patches promptly once available. 7) Consider network-level protections such as DNS filtering and anomaly detection to identify and block suspicious DNS traffic that could result from exploitation attempts.