CVE-2026-20257 | 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.

Published: 2026-06-10 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-20257 is rated Low Risk (26.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.19%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-20257

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.19% +0.15%
2 2026-06-11 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-20257

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.7 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.1 3.6 [email protected]

Weakness enumeration for CVE-2026-20257

GitHub Security Advisory for CVE-2026-20257

GHSA-73fj-f5qc-x4jf · Severity: medium — In Splunk Enterprise versions below 10.2.4, 10.0.7, 9.4.12, and 9.3.13, and Splunk Cloud Platform...

Affected software / configurations for CVE-2026-20257

Vendor Product Version Raw CPE
splunk splunk >= 9.3.0, < 9.3.13 cpe:2.3:a:splunk:splunk:*:*:*:*:enterprise:*:*:*
splunk splunk >= 9.4.0, < 9.4.12 cpe:2.3:a:splunk:splunk:*:*:*:*:enterprise:*:*:*
splunk splunk >= 10.0.0, < 10.0.7 cpe:2.3:a:splunk:splunk:*:*:*:*:enterprise:*:*:*
splunk splunk >= 10.2.0, < 10.2.4 cpe:2.3:a:splunk:splunk:*:*:*:*:enterprise:*:*:*
splunk splunk_cloud_platform >= 9.3.2411, < 9.3.2411.132 cpe:2.3:a:splunk:splunk_cloud_platform:*:*:*:*:*:*:*:*
splunk splunk_cloud_platform >= 10.1.2507, < 10.1.2507.23 cpe:2.3:a:splunk:splunk_cloud_platform:*:*:*:*:*:*:*:*
splunk splunk_cloud_platform >= 10.2.2510, < 10.2.2510.15 cpe:2.3:a:splunk:splunk_cloud_platform:*:*:*:*:*:*:*:*
splunk splunk_cloud_platform >= 10.3.2512, < 10.3.2512.13 cpe:2.3:a:splunk:splunk_cloud_platform:*:*:*:*:*:*:*:*

References for CVE-2026-20257

cvelogic Threat Intelligence