Medium

Data exfiltration via incomplete external content URL validation in Splunk classic dashboards

IdentifiersCVE-2026-20255CWE-20· Improper Input Validation

CVE-2026-20255 affects 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. The flaw exists in classic dashboards because URL validation in the external content dialog is incomplete. A low-privileged Splunk user who does not have the "admin" or "power" role can craft a malicious classic dashboard that causes requests to be made to untrusted external domains when another user interacts with the dashboard. This improper input validation can be abused to exfiltrate sensitive data from Splunk Web contexts to an attacker-controlled server.

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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 sensitive data exposure and exfiltration to an external server. Based on the provided context, the malicious dashboard can cause a victim user interacting with the dashboard to send sensitive data, potentially including session-related data or other information accessible in the dashboard context, to attacker-controlled infrastructure. The issue primarily affects Splunk Web components and is especially concerning when higher-privileged users interact with attacker-crafted dashboards.

Mitigation

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

If immediate patching is not possible, restrict creation and modification of classic dashboards to trusted users, reduce or remove low-privileged users' ability to introduce dashboard content, enforce strict trusted-domain controls, monitor for suspicious dashboards and unexpected outbound requests to untrusted domains, and disable or limit Splunk Web exposure where operationally feasible.

Remediation

Patch, then assume compromise.

Upgrade Splunk Enterprise to 10.2.4, 10.0.7, 9.4.12, or 9.3.13 or later. Upgrade Splunk Cloud Platform to 10.3.2512.13, 10.2.2510.15, 10.1.2507.23, or 9.3.2411.132 or later.

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

SplunkSplunkapplication

SplunkSplunk Cloud Platformapplication

SplunkSplunk Enterpriseapplication

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 external content dialog validation that can enable data exfiltration to untrusted domains.

What this page doesn’t show

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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-2026-20255

NVD

nvd.nist.gov/vuln/detail/CVE-2026-20255

MITRE CWE · CWE-20

Improper Input Validation

Vendor Advisory

advisory.splunk.com/advisories/SVD-2026-0605