Medium

Splunk classic dashboard CSS injection external content restriction bypass

IdentifiersCVE-2026-20254CWE-20· Improper Input Validation

CVE-2026-20254 is an improper input validation vulnerability in classic dashboards affecting 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 Splunk user without the 'admin' or 'power' roles can craft a malicious classic dashboard that abuses Cascading Style Sheets (CSS) injection to bypass Splunk's external content restriction. The root issue described is that the Trusted Domains security check does not fully validate inline style attribute values. When a higher-privileged user views the crafted dashboard, the injected CSS can trigger outbound requests to attacker-controlled infrastructure, enabling exfiltration of sensitive data and potentially credentials.

For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

Start free trial

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a low-privileged user to leverage a higher-privileged user's dashboard view to cause the victim's browser to make outbound requests to untrusted external domains. This can result in exfiltration of sensitive data and credentials or session-related information accessible in the viewing context. The vulnerability undermines trusted-domain enforcement for classic dashboards and creates a privilege-crossing data exposure path from low-privileged content authors to higher-privileged viewers.

Mitigation

If you can’t patch tonight, do this now.

Until patches are fully deployed, restrict dashboard creation and editing permissions to trusted users, especially for classic dashboards. Enforce strict trusted-domain policies, review and limit Splunk Web exposure, and disable Splunk Web where it is not operationally required. Closely monitor for suspicious or newly created dashboards and outbound requests initiated from dashboard views to unexpected domains. Where feasible, reduce use of classic dashboards by untrusted or low-privileged users.

Remediation

Patch, then assume compromise.

Upgrade Splunk Enterprise to 10.2.4 or later, 10.0.7 or later, 9.4.12 or later, or 9.3.13 or later. Upgrade Splunk Cloud Platform to 10.3.2512.13 or later, 10.2.2510.15 or later, 10.1.2507.23 or later, or 9.3.2411.132 or later. Apply the vendor fixes that correct validation of inline style attribute values and close the trusted-domain bypass in classic dashboards.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

SplunkCloud Platformapplication

SplunkEnterpriseapplication

SplunkSplunkapplication

SplunkSplunk Cloud Platformapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

1 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

1 SOURCESView more in app

cyber security newsNews

Jun 11, 2026

Multiple Splunk Enterprise Vulnerabilities Allow Attackers to Execute Malicious Script

A medium-severity improper input validation vulnerability in Splunk Enterprise classic dashboards involving CSS restriction bypass that can enable credential and data exfiltration.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

Start free trial

Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-20254

NVD

nvd.nist.gov/vuln/detail/CVE-2026-20254

MITRE CWE · CWE-20

Improper Input Validation

Vendor Advisory

advisory.splunk.com/advisories/SVD-2026-0604