CVE-2025-20324 is a medium-severity vulnerability affecting multiple versions of Splunk Enterprise (below 9.4.2, 9.3.5, 9.2.7, and 9.1.10) and Splunk Cloud Platform (below 9.3.2411.104, 9.3.2408.113, and 9.2.2406.119). The vulnerability arises because the software does not properly restrict access to the creation or overwriting of system source type configurations via the REST API endpoint `/servicesNS/nobody/search/admin/sourcetypes/` on the Splunk management port. Specifically, a low-privileged user lacking the "admin" or "power" roles can send a specially crafted payload to this endpoint and manipulate source type configurations. Source types in Splunk define how incoming data is parsed and indexed, so unauthorized modification could lead to data misinterpretation, potential data integrity issues, or evasion of detection mechanisms. The CVSS 3.1 base score is 5.4 (medium), reflecting that the attack vector is network-based (AV:N), requires low privileges (PR:L), no user interaction (UI:N), and impacts confidentiality and integrity to a limited extent (C:L/I:L/A:N). There are no known exploits in the wild as of the publication date. The vulnerability does not require admin-level privileges but does require some authenticated access with a low-privileged account, which lowers the barrier for exploitation within compromised or insider environments. This flaw could be leveraged by malicious insiders or attackers who have gained limited access to the Splunk environment to alter how data is ingested and interpreted, potentially masking malicious activity or corrupting logs used for security monitoring and forensic analysis. No patches or mitigation links were provided in the source information, but upgrading to fixed versions (9.4.2 or later, etc.) is implied as the remediation path.

For European organizations, this vulnerability poses a risk to the integrity and reliability of security monitoring and log management systems. Splunk is widely used in Europe for security information and event management (SIEM), compliance reporting, and operational intelligence. Unauthorized modification of source type configurations could allow attackers to evade detection by altering how logs are parsed or to inject misleading data, undermining incident response and compliance efforts (e.g., GDPR audit requirements). The confidentiality impact is limited but still relevant if sensitive log data is exposed or manipulated. The vulnerability could also disrupt operational processes dependent on accurate data ingestion. Organizations in regulated sectors such as finance, healthcare, and critical infrastructure in Europe could face increased risk of undetected breaches or compliance violations. Although exploitation requires some level of authenticated access, insider threats or compromised low-privileged accounts could leverage this vulnerability to escalate the impact of their activities. The absence of known exploits suggests a window of opportunity for defenders to patch and harden systems before active attacks emerge.

European organizations should prioritize upgrading affected Splunk Enterprise and Cloud Platform instances to the fixed versions (9.4.2 or later for Enterprise, and corresponding Cloud Platform versions) as soon as possible. In the interim, organizations should audit and restrict access to Splunk roles, ensuring that low-privileged users do not have unnecessary access to the management REST API endpoints. Implement strict role-based access controls (RBAC) and monitor API usage for anomalous requests targeting `/servicesNS/nobody/search/admin/sourcetypes/`. Employ network segmentation and firewall rules to limit access to the Splunk management port to trusted administrators and systems only. Additionally, enable and review Splunk audit logs to detect unauthorized configuration changes. Conduct regular reviews of source type configurations to identify unexpected modifications. Incorporate this vulnerability into incident response plans and threat hunting activities to detect potential exploitation attempts. Finally, maintain up-to-date vulnerability management processes to track and apply vendor patches promptly.