Overview
CVE-2025-20389 describes a medium-severity client-side Denial of Service (DoS) vulnerability found in Splunk Secure Gateway when used with Splunk Enterprise and Splunk Cloud Platform. This vulnerability allows a low-privileged user without “admin” or “power” roles to craft a malicious payload within the `label` column field when adding a new device. This crafted payload can then trigger a DoS condition within the application’s client-side components.
Technical Details
The vulnerability resides in the Splunk Secure Gateway app’s device management functionality. A low-privileged user can add a new device and, critically, manipulate the `label` field to include a payload designed to consume excessive resources or trigger errors when the application attempts to render or process it. Because the payload is rendered in the client’s browser, the attack primarily affects the user interface and may make the application unusable for the affected user. The specific nature of the payload that triggers the DoS is not detailed in the advisory, but it likely involves overly complex JavaScript, excessively large strings, or other client-side resource exhaustion techniques.
Affected Versions:
- Splunk Enterprise versions below 10.0.2
- Splunk Enterprise versions below 9.4.6
- Splunk Enterprise versions below 9.3.8
- Splunk Enterprise versions below 9.2.10
- Splunk Secure Gateway app on Splunk Cloud Platform versions below 3.9.10
- Splunk Secure Gateway app on Splunk Cloud Platform versions below 3.8.58
- Splunk Secure Gateway app on Splunk Cloud Platform versions below 3.7.28
CVSS Analysis
The National Vulnerability Database (NVD) has assigned CVE-2025-20389 a CVSS score of 4.3, indicating a medium severity vulnerability. The CVSS vector likely reflects the following characteristics:
- Attack Vector (AV): Network (N) – The attack can be initiated remotely.
- Attack Complexity (AC): Low (L) – Exploitation requires little to no specialized knowledge or access.
- Privileges Required (PR): Low (L) – A user with basic privileges can exploit the vulnerability.
- User Interaction (UI): Required (R) – The victim needs to interact with the malicious payload (e.g., viewing the affected device).
- Scope (S): Unchanged (U) – The vulnerability affects only the vulnerable component (the Splunk Secure Gateway app).
- Confidentiality Impact (C): None (N) – The vulnerability does not expose sensitive information.
- Integrity Impact (I): None (N) – The vulnerability does not allow modification of data.
- Availability Impact (A): Low (L) – The vulnerability can cause a partial disruption of service.
The score reflects the localized nature of the DoS (affecting only the user interface) and the requirement for user interaction.
Possible Impact
The primary impact of CVE-2025-20389 is a client-side Denial of Service (DoS). While not affecting the underlying Splunk platform or data integrity, a successful exploit can render the Splunk Secure Gateway app unusable for the affected user. This can disrupt their ability to manage and monitor devices connected through the Secure Gateway, potentially hindering security operations and incident response.
Even though the vulnerability requires user interaction, social engineering tactics could be employed to trick users into viewing the crafted payload, increasing the likelihood of successful exploitation.
Mitigation or Patch Steps
The recommended mitigation is to upgrade your Splunk Enterprise and Splunk Secure Gateway app installations to the patched versions:
- Upgrade Splunk Enterprise to version 10.0.2 or later.
- Upgrade Splunk Enterprise to version 9.4.6 or later.
- Upgrade Splunk Enterprise to version 9.3.8 or later.
- Upgrade Splunk Enterprise to version 9.2.10 or later.
- Upgrade the Splunk Secure Gateway app on Splunk Cloud Platform to version 3.9.10 or later.
- Upgrade the Splunk Secure Gateway app on Splunk Cloud Platform to version 3.8.58 or later.
- Upgrade the Splunk Secure Gateway app on Splunk Cloud Platform to version 3.7.28 or later.
Follow the standard Splunk upgrade procedures and thoroughly test the updated environment before deploying to production.
