CVE-2026-20257: splunk Input Validation Flaw — Fix

Description

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.

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CVSS v3.1 Score

5.7

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

EPSS — Exploit Prediction

0.0020

Probability of exploitation

0.10%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

Affected Products

Vendor	Product	Versions
splunk	splunk	9.3.0 — 9.3.13
splunk	splunk	9.4.0 — 9.4.12
splunk	splunk	10.0.0 — 10.0.7
splunk	splunk	10.2.0 — 10.2.4
splunk	splunk_cloud_platform	9.3.2411 — 9.3.2411.132
splunk	splunk_cloud_platform	10.1.2507 — 10.1.2507.23
splunk	splunk_cloud_platform	10.2.2510 — 10.2.2510.15
splunk	splunk_cloud_platform	10.3.2512 — 10.3.2512.13

References

Advisories & Patches

https://advisory.splunk.com/advisories/SVD-2026-0607

Frequently Asked Questions

What is CVE-2026-20257? +

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. It has a CVSS v3.1 base score of 5.7 (MEDIUM).

How severe is CVE-2026-20257? +

CVE-2026-20257 has a CVSS v3.1 score of 5.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0020, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-20257? +

CVE-2026-20257 affects products from splunk, specifically: splunk, splunk_cloud_platform. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-20257? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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