CVE-2024-21673 is a high severity Remote Code Execution (RCE) vulnerability affecting Atlassian Confluence Data Center and Server versions starting from 7.13.0 onward, including multiple subsequent versions up to 8.7.1. The vulnerability is classified under CWE-94, which relates to improper control of code generation, indicating that the flaw allows an attacker to execute arbitrary code on the affected system. The CVSS v3.0 score is 8.0, reflecting a high severity level. The vector string CVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H indicates that the attack can be performed remotely over the network (AV:N) but requires high attack complexity (AC:H) and privileges (PR:H), with no user interaction needed (UI:N). The scope is changed (S:C), meaning the vulnerability affects resources beyond the initially vulnerable component. The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning successful exploitation can lead to full system compromise, data exposure, and service disruption. The vulnerability allows an authenticated attacker with elevated privileges to execute arbitrary code remotely, potentially leading to complete takeover of the Confluence server environment. Atlassian recommends upgrading to fixed versions: 7.19.18 or higher in the 7.19.x branch, 8.5.5 or higher in the 8.5.x branch, or 8.7.2 or higher in the 8.7.x branch. No known exploits in the wild have been reported yet, but the high impact and the widespread use of Confluence Data Center in enterprise environments make this a critical issue to address promptly.

For European organizations, this vulnerability poses a significant risk due to the widespread adoption of Atlassian Confluence Data Center in enterprise collaboration and documentation environments. Successful exploitation could lead to unauthorized access to sensitive corporate information, intellectual property theft, disruption of business operations, and potential lateral movement within the network. Given the high impact on confidentiality, integrity, and availability, attackers could manipulate or delete critical data, disrupt collaboration workflows, or deploy ransomware or other malware payloads. The requirement for authenticated access with high privileges limits the attack surface but does not eliminate risk, as insider threats or compromised credentials could be leveraged. The vulnerability’s ability to change scope means attackers could escalate privileges or affect other components beyond Confluence itself, amplifying the damage. This is particularly concerning for sectors with strict data protection regulations such as GDPR, where data breaches can lead to heavy fines and reputational damage. Additionally, the lack of user interaction required for exploitation facilitates automated or scripted attacks once credentials are obtained.

European organizations should prioritize immediate patching of Confluence Data Center and Server instances by upgrading to the recommended fixed versions: 7.19.18 or later, 8.5.5 or later, or 8.7.2 or later. If immediate patching is not feasible, organizations should implement strict access controls to limit administrative privileges to trusted personnel only and enforce multi-factor authentication (MFA) for all Confluence accounts with elevated privileges to reduce the risk of credential compromise. Network segmentation should be employed to isolate Confluence servers from critical infrastructure and sensitive data repositories. Monitoring and logging of Confluence access and administrative actions should be enhanced to detect anomalous behavior indicative of exploitation attempts. Additionally, organizations should review and harden their Confluence configurations, disable unnecessary plugins or integrations, and regularly audit user permissions. Incident response plans should be updated to include scenarios involving Confluence compromise. Finally, organizations should consider deploying web application firewalls (WAFs) with rules tuned to detect and block suspicious requests targeting Confluence vulnerabilities.