Splunk Classic Dashboard Style Attribute Validation Exfiltration (10.3)
CVE-2026-20257 Published on June 10, 2026
Improper Input Validation through Classic Dashboard CSS in Splunk Enterprise
In Splunk Enterprise versions below 10.2.4, 10.0.7, 9.4.12, and 9.3.13, and Splunk Cloud Platform versions below 10.3.2512.13, 10.2.2510.15, 10.1.2507.23, and 9.3.2411.132, a low-privileged user that does not hold the "admin" or "power" Splunk roles could craft a classic dashboard that exfiltrates sensitive data from the browser of a higher-privileged user who views it.
The exfiltration is possible because classic dashboard panels do not fully validate style attribute values, which can allow for requests to reach external domains outside the configured Trusted Domains List.
The vulnerability requires the attacker to phish the victim by tricking them into initiating a request within their browser. The low-privileged user should not be able to exploit the vulnerability at will.
Weakness Type
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Products Associated with CVE-2026-20257
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Affected Versions
Splunk Enterprise:- Version 10.2 and below 10.2.4 is affected.
- Version 10.0 and below 10.0.7 is affected.
- Version 9.4 and below 9.4.12 is affected.
- Version 9.3 and below 9.3.13 is affected.
- Version 10.3.2512 and below 10.3.2512.13 is affected.
- Version 10.2.2510 and below 10.2.2510.15 is affected.
- Version 10.1.2507 and below 10.1.2507.23 is affected.
- Version 9.3.2411 and below 9.3.2411.132 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.