CVE-2025-22166 is a Denial of Service vulnerability identified in Atlassian Confluence Data Center, a widely used enterprise collaboration platform. The flaw was introduced in version 2.0 and affects multiple versions spanning from 7.19.16 through various 8.x and 9.x releases, up to but not including the patched versions 8.5.25, 9.2.7, and 10.0.2. The vulnerability allows an attacker to cause resource unavailability by exploiting a flaw that disrupts the service operations of the host running Confluence Data Center. According to the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H), the attack can be performed remotely over the network with low complexity, requires low privileges but no user interaction, and results in a high impact on availability. The vulnerability does not affect confidentiality or integrity directly but can severely impact business continuity by making Confluence services inaccessible. Atlassian has addressed the issue in recent releases and strongly recommends upgrading to these fixed versions. No public exploits have been observed yet, but the high severity and ease of exploitation make this a critical patching priority. The vulnerability was responsibly disclosed internally to Atlassian, indicating a controlled disclosure process.

For European organizations, the impact of CVE-2025-22166 can be substantial, particularly for enterprises and public sector entities relying heavily on Confluence Data Center for collaboration, documentation, and knowledge management. A successful DoS attack could disrupt internal communications, delay project timelines, and reduce operational efficiency. Critical sectors such as finance, healthcare, government, and manufacturing that depend on Confluence for real-time collaboration may face operational outages, potentially affecting service delivery and compliance with regulatory requirements. The disruption could also impact remote work capabilities, which remain vital post-pandemic. Additionally, organizations with integrated Confluence instances in their IT service management or DevOps pipelines may experience cascading effects. While no data breach is implied, the availability loss can lead to reputational damage and financial losses. The ease of exploitation and network accessibility increase the risk of opportunistic attacks, especially in environments with exposed Confluence endpoints.

1. Immediate upgrade to Atlassian Confluence Data Center versions 8.5.25, 9.2.7, 10.0.2 or later to apply the official patch addressing CVE-2025-22166. 2. If immediate upgrade is not feasible, implement network-level controls such as IP whitelisting and firewall rules to restrict access to Confluence instances only to trusted internal networks and VPN users. 3. Monitor Confluence server logs and network traffic for unusual spikes or patterns indicative of DoS attempts, including repeated requests or resource exhaustion symptoms. 4. Employ rate limiting and web application firewall (WAF) rules tailored to Confluence endpoints to mitigate potential attack vectors. 5. Conduct regular backups of Confluence data and configurations to enable rapid recovery in case of service disruption. 6. Review and minimize user privileges to reduce the attack surface, ensuring that only necessary users have access to Confluence administration functions. 7. Coordinate with Atlassian support and subscribe to security advisories for timely updates on related vulnerabilities or exploits. 8. Incorporate Confluence availability monitoring into broader incident response and business continuity plans to ensure rapid detection and remediation.