CVE-2025-20371
📋 TL;DR
This vulnerability allows unauthenticated attackers to perform blind server-side request forgery (SSRF) against vulnerable Splunk deployments, potentially enabling them to make REST API calls with the privileges of authenticated high-privileged users. It affects Splunk Enterprise versions below 10.0.1, 9.4.4, 9.3.6 and 9.2.8, and Splunk Cloud Platform versions below specific patch levels.
💻 Affected Systems
- Splunk Enterprise
- Splunk Cloud Platform
📦 What is this software?
Splunk by Splunk
Splunk by Splunk
Splunk by Splunk
Splunk by Splunk
⚠️ Risk & Real-World Impact
Worst Case
Attackers could perform administrative REST API operations, potentially leading to data exfiltration, configuration changes, or further system compromise.
Likely Case
Attackers could probe internal networks, access internal services, or perform limited API operations depending on network configuration.
If Mitigated
With proper network segmentation and authentication controls, impact would be limited to information disclosure about internal network services.
🎯 Exploit Status
Exploitation requires no authentication and appears to be straightforward based on advisory description.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Splunk Enterprise: 10.0.1, 9.4.4, 9.3.6, 9.2.8; Splunk Cloud Platform: 9.3.2411.109, 9.3.2408.119, 9.2.2406.122
Vendor Advisory: https://advisory.splunk.com/advisories/SVD-2025-1006
Restart Required: Yes
Instructions:
1. Download appropriate patch version from Splunk downloads portal. 2. Backup current installation. 3. Stop Splunk services. 4. Apply patch according to Splunk upgrade documentation. 5. Restart Splunk services. 6. Verify successful upgrade.
🔧 Temporary Workarounds
Network Access Control
allRestrict network access to Splunk management interfaces to trusted IP addresses only.
# Configure firewall rules to restrict access to Splunk ports (default: 8000, 8089)
# Example iptables: iptables -A INPUT -p tcp --dport 8000 -s trusted_network -j ACCEPT
# Example iptables: iptables -A INPUT -p tcp --dport 8089 -s trusted_network -j ACCEPT
Authentication Enforcement
allEnsure all REST API endpoints require authentication, though this may not fully mitigate SSRF.
# Review and configure authentication settings in web.conf and server.conf
# Ensure [settings] authentication = Splunk in web.conf
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Splunk instances from sensitive internal services
- Deploy web application firewall (WAF) rules to detect and block SSRF patterns
🔍 How to Verify
Check if Vulnerable:
Check Splunk version via web interface (Settings > Server Info) or command line. Compare against affected versions list.Check Version:
On Splunk server: $SPLUNK_HOME/bin/splunk versionVerify Fix Applied:
Verify version is at or above patched versions after upgrade. Test REST API endpoints for SSRF behavior.📡 Detection & Monitoring
Log Indicators:
- Unusual REST API calls from unauthenticated sources
- Unexpected outbound connections from Splunk server
- Failed authentication attempts followed by API calls
Network Indicators:
- HTTP requests to internal services originating from Splunk server
- Unusual traffic patterns on Splunk management ports (8000, 8089)
SIEM Query:
index=_internal source=*web_access.log (status=200 OR status=302) AND (uri_path=*/services/* OR uri_path=*/api/*) AND clientip NOT IN [list_of_trusted_ips]