CVE-2026-20239
Sensitive Data Exposure in Splunk Enterprise and Splunk Cloud Platform
Publication date: 2026-05-20
Last updated on: 2026-05-20
Assigner: Cisco Systems, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| splunk | splunk_enterprise | to 10.0.5 (exc) |
| splunk | splunk_cloud_platform | to 10.0.2503.13 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-532 | The product writes sensitive information to a log file. |
Attack-Flow Graph
AI Powered Q&A
How can this vulnerability impact me? :
This vulnerability can lead to sensitive information disclosure, including session cookies and response bodies, to users who have access to the _internal index.
Such exposure can compromise confidentiality, potentially allowing attackers or unauthorized users to hijack sessions or access sensitive data.
How can this vulnerability be detected on my network or system? Can you suggest some commands?
No official detection methods or specific commands have been provided for identifying this vulnerability on your network or system.
Can you explain this vulnerability to me?
CVE-2026-20239 is a high-severity vulnerability in Splunk Enterprise and Splunk Cloud Platform versions below certain releases. It allows a user with access to the _internal index to view sensitive information such as session cookies and response bodies.
The root cause is missing output buffer sanitization in the TcpChannel component, which logs full input/output buffer contents at WARN level during socket errors, exposing sensitive data in log files.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, it is recommended to upgrade Splunk Enterprise to version 10.2.2 or later, and Splunk Cloud Platform to versions 10.3.2512.8, 10.2.2510.11, 10.1.2507.21, or 10.0.2503.13 or later.
Alternatively, restrict access to the _internal index to administrator-level roles only to reduce the risk of sensitive data exposure.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
This vulnerability allows users with access to the _internal index to view session cookies and response bodies containing sensitive data due to missing output buffer sanitization. Such exposure of sensitive information can lead to non-compliance with data protection regulations like GDPR and HIPAA, which mandate the protection of personal and sensitive data from unauthorized access or disclosure.
To mitigate this risk and help maintain compliance, it is recommended to upgrade to the latest versions of Splunk Enterprise or Splunk Cloud Platform or restrict access to the _internal index to administrator-level roles only.