CVE-2025-22166: 
Confluence Server 脆弱性の分析と軽減

CVE-2025-22166 is a Denial of Service (DoS) vulnerability in Atlassian Confluence Data Center and Server, introduced in version 2.0 of Confluence Data Center. It was disclosed on October 21, 2025, via Atlassian's monthly Security Bulletin and was reported through Atlassian's internal program. Affected versions include Confluence Data Center and Server 8.5.0–8.5.24, 9.2.0–9.2.6, and 10.0.0–10.0.1, among other intermediate releases. The vulnerability carries a CVSS v3.1 base score of 7.5 (High) and a CVSS v4.0 base score of 8.3 (High) (Atlassian Security Bulletin, Feedly).

The vulnerability is classified as CWE-405 (Asymmetric Resource Consumption / Amplification), meaning an attacker can send relatively low-cost requests that cause disproportionately high resource consumption on the server. The attack vector is network-based, requires no privileges (CVSS v3.1) or low privileges (CVSS v4.0), no user interaction, and has low attack complexity, making it straightforward to exploit remotely. The specific component or endpoint triggering the amplification has not been publicly detailed, as the vulnerability was reported via Atlassian's internal program rather than through external bug bounty disclosure (Atlassian Security Bulletin, Feedly).

Successful exploitation allows an attacker to make Confluence Data Center or Server instances temporarily or indefinitely unavailable to legitimate users, resulting in a high availability impact with no confidentiality or integrity compromise. The attack can be executed remotely without authentication (per CVSS v3.1 scoring), potentially causing complete service disruption for organizations relying on Confluence for collaboration and documentation. There is no evidence of lateral movement or data exfiltration risk associated with this vulnerability (Atlassian Security Bulletin, Feedly).

Atlassian recommends upgrading to the latest available version. Specific fixed versions are:

• Confluence Data Center and Server 8.5: Upgrade to 8.5.25 or later
• Confluence Data Center and Server 9.2: Upgrade to 9.2.7 or later
• Confluence Data Center and Server 10.0: Upgrade to 10.0.2 or later

As interim mitigations, organizations should restrict network access to Confluence instances, implement network segmentation, and monitor for unusual service degradation or performance anomalies. No configuration-based workaround has been published by Atlassian (Atlassian Security Bulletin, Feedly).

The vulnerability was included in Atlassian's October 21, 2025 Security Bulletin and was also referenced in the November 18, 2025 bulletin for general awareness, as the fix was released post-publication of the October bulletin. Coverage has been limited to vulnerability aggregation platforms and security news outlets, with no notable independent researcher commentary or significant social media discussion identified (Atlassian Security Bulletin, Atlassian Nov Bulletin).