CVE-2025-20371 is a high-severity vulnerability affecting multiple versions of Splunk Enterprise (below 10.0.1, 9.4.4, 9.3.6, and 9.2.8) and Splunk Cloud Platform (below 9.3.2411.109, 9.3.2408.119, and 9.2.2406.122). The vulnerability arises because the web server component of Splunk Enterprise does not adequately validate URLs or similar requests received from upstream components before retrieving their contents. This insufficient validation enables an unauthenticated attacker to trigger a blind server-side request forgery (SSRF). Through SSRF, the attacker can coerce the vulnerable server to send crafted REST API calls on behalf of an authenticated high-privileged user, potentially bypassing authentication and authorization controls. The CVSS 3.1 base score is 7.5, indicating a high severity, with the vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H. This means the attack can be launched remotely over the network without privileges but requires some user interaction. The attack complexity is high, but the impact on confidentiality, integrity, and availability is high if exploited. The vulnerability could allow attackers to access sensitive data, modify or delete critical information, or disrupt service availability by abusing REST API calls. Although no known exploits are currently reported in the wild, the potential for exploitation exists given the widespread use of Splunk Enterprise in enterprise environments for security monitoring and log management. This vulnerability is particularly concerning because it can be exploited without authentication, leveraging the trust relationship between the Splunk server and its upstream components or internal services. Organizations using affected versions should prioritize patching or upgrading to fixed versions to mitigate this risk.

For European organizations, the impact of CVE-2025-20371 could be significant due to the widespread adoption of Splunk Enterprise for security information and event management (SIEM), operational intelligence, and compliance monitoring. Exploitation of this SSRF vulnerability could lead to unauthorized access to sensitive internal systems and data, including personal data protected under GDPR. Attackers could perform unauthorized REST API calls with high privileges, potentially leading to data breaches, manipulation of logs or security alerts, and disruption of monitoring capabilities. This could impair incident detection and response, increasing the risk of further compromise. Additionally, the ability to perform SSRF attacks may allow attackers to pivot within internal networks, targeting other critical infrastructure components. The confidentiality, integrity, and availability of critical business and security data could be severely impacted, resulting in regulatory penalties, reputational damage, and operational downtime. Given the high integration of Splunk in security operations centers (SOCs) across Europe, this vulnerability poses a substantial risk to the security posture of affected organizations.

1. Immediate upgrade: Organizations should upgrade Splunk Enterprise and Splunk Cloud Platform to the fixed versions (10.0.1 or later, 9.4.4 or later, 9.3.6 or later, and 9.2.8 or later) as soon as possible to remediate the vulnerability. 2. Network segmentation: Restrict network access to Splunk management interfaces and internal services to trusted hosts and networks only, minimizing exposure to untrusted sources. 3. Input validation and filtering: Implement strict input validation and filtering on any upstream components or proxies that send URLs or requests to the Splunk server to prevent malicious or unexpected requests. 4. Monitor logs and alerts: Enhance monitoring for unusual REST API activity or unexpected outbound requests from Splunk servers that could indicate exploitation attempts. 5. Access controls: Review and tighten access controls for REST API usage, ensuring that only authorized users and systems have necessary permissions. 6. User interaction minimization: Since the attack requires user interaction, educate users and administrators about phishing and social engineering risks that could trigger SSRF exploitation. 7. Incident response readiness: Prepare incident response plans specific to SSRF exploitation scenarios, including containment and forensic analysis procedures. These targeted mitigations go beyond generic advice by focusing on the specific attack vector and operational context of Splunk deployments.