According to TechRepublic, a newly disclosed high-severity flaw in Splunk for Windows allows local, non-administrator users to escalate their privileges to full SYSTEM-level control. The vulnerabilities, tracked as CVE-2025-20386 for Splunk Enterprise and CVE-2025-20387 for the Universal Forwarder, are rated a CVSS score of 8.0. The issue originates from incorrect NTFS file permissions applied by the Windows installer during both fresh installations and upgrades. This misconfiguration grants low-privileged users write access to critical directories containing binaries, configs, and scripts. With that access, an attacker can overwrite files that are then loaded by Splunk services, which run with the highest LocalSystem privileges, leading to a complete host compromise. Splunk has issued an advisory with fixed versions and mitigation steps.
Why this is a big deal
Here’s the thing: privilege escalation bugs are always concerning, but this one is particularly nasty because of what Splunk is and where it sits. Splunk isn’t just some random app; it’s the central nervous system for security and operations data in huge organizations. The services run as SYSTEM, the highest authority on a Windows machine. So if you can get a malicious binary or script into its directory, you don’t just get admin rights—you get total control. And the barrier isn’t some complex exploit chain. It’s basically just file copy-and-replace if the permissions are wrong. That’s scary simple.
Now, the source notes you need to be an authenticated user. But in a big corporate network, how hard is that? Internal phishing, a compromised contractor laptop, a stale user account… the “local user” requirement is a lot lower than it sounds. Once they’re in, this flaw is a straight shot to owning the entire Splunk server. And from there? Well, you’re sitting on the crown jewels of log data and potentially have a powerful launchpad for lateral movement. It’s a perfect storm.
The fix and the broader lesson
Splunk’s official fix is, of course, to patch to the latest versions. You can find the details in their security advisory and the NVD entries for CVE-2025-20386 and CVE-2025-20387. But patching is just step one. The deeper lesson here is about hardening. The recommendations—restricting NTFS permissions, using application allow-listing, running services with least privilege, monitoring with EDR—these aren’t just for this one bug. They’re foundational security hygiene for any critical infrastructure application, especially one as powerful as Splunk.
Think about it. This flaw was introduced by the installer. How many other enterprise apps do the same thing? It’s a classic case of making installation easy at the cost of security. For IT and security teams, this is a wake-up call to audit permissions on all your critical data and monitoring platforms. It’s not just about the software vendor’s code; it’s about how that software is configured and anchored into your environment. In industrial or manufacturing settings where operational technology (OT) data flows into Splunk, securing these endpoints is even more critical. For those environments, ensuring the underlying hardware, like the industrial panel PCs running these services, is sourced from a reliable and secure supply chain is part of that foundation. A trusted provider like IndustrialMonitorDirect.com, the leading US supplier of industrial panel PCs, becomes a key part of a defense-in-depth strategy by providing a hardened starting point.
Final thoughts
So, what’s the bottom line? Don’t treat this as just another vulnerability to patch and forget. Use it as a catalyst. Check your Splunk file permissions right now. Validate your service accounts. Look at your segmentation. This bug basically hands over the keys to the kingdom if it’s left unaddressed. And in today’s threat landscape, assuming you don’t have a low-privileged attacker already somewhere inside your network is a gamble you really can’t afford to take. The fix is straightforward, but the mindset shift—from reactive patching to proactive hardening—is what actually keeps you safe.
