CVE-2025-20369 is a medium-severity vulnerability affecting Splunk Enterprise and Splunk Cloud Platform versions prior to 9.4.4, 9.3.6, 9.2.8, and corresponding cloud versions. The vulnerability arises from improper handling of XML documents that allow Document Type Definitions (DTDs) with recursive entity definitions. Specifically, a low-privilege user without admin or power roles can exploit an XML External Entity (XXE) injection via the dashboard tab label field. This XXE injection can lead to denial of service (DoS) conditions by causing resource exhaustion or application crashes due to uncontrolled recursive entity expansion. The vulnerability does not impact confidentiality but affects integrity and availability. Exploitation requires network access (AV:N), low attack complexity (AC:L), low privileges (PR:L), and user interaction (UI:R). The scope is unchanged (S:U), meaning the impact is limited to the vulnerable component. The CVSS score is 4.6, reflecting a medium severity. No known exploits are currently in the wild, but the vulnerability's presence in widely deployed Splunk versions makes it a notable risk. The vulnerability stems from XML parsing flaws that allow maliciously crafted input to trigger recursive entity expansion, a classic XXE attack vector leading to DoS. Since Splunk is a critical log management and SIEM platform, such disruptions can impact security monitoring and incident response capabilities.

For European organizations, the impact of this vulnerability can be significant given Splunk's widespread use in enterprise environments for security monitoring, operational intelligence, and compliance reporting. A successful DoS attack could disrupt log ingestion, alerting, and dashboard functionalities, impairing security teams' ability to detect and respond to incidents promptly. This could increase the risk of undetected breaches or delayed responses to ongoing attacks. Additionally, availability issues in Splunk could affect compliance with regulatory requirements such as GDPR, which mandates timely incident detection and response. Organizations relying heavily on Splunk for operational continuity may experience service degradation or outages, impacting business operations and potentially causing financial and reputational damage. Although the vulnerability does not allow data exfiltration or privilege escalation, the denial of service impact on a critical security platform is a serious concern for European enterprises.

To mitigate this vulnerability, European organizations should prioritize upgrading affected Splunk Enterprise and Cloud Platform instances to versions 9.4.4, 9.3.6, 9.2.8 or later, where the issue is resolved. Until patches are applied, organizations should restrict dashboard editing permissions to trusted users only, minimizing the risk of malicious input via the dashboard tab label field. Implement strict input validation and sanitization on XML inputs where possible. Network segmentation and access controls should limit exposure of Splunk management interfaces to only authorized personnel and systems. Monitoring for unusual dashboard configuration changes or spikes in resource usage can help detect exploitation attempts. Additionally, organizations should review and harden XML parser configurations to disable DTD processing or limit entity expansions if feasible. Regular security audits and vulnerability scanning of Splunk deployments will help identify unpatched instances. Finally, maintaining an incident response plan that includes recovery from Splunk service disruptions will reduce operational impact.