5.7

CVE-2026-20256: splunk Improper Input Validation

CVSS: 5.7v3.1MediumAnalyzed
Published 10-06-2026Last modified 10-06-2026
Open JSON

Vulnerability summary

CVE-2026-20256 is a medium (CVSS 5.7) Improper Input Validation vulnerability in splunk. EPSS estimates a 0.36% chance of exploitation in the next 30 days, higher than 28.4% of scored vulnerabilities.

Overall risk
23/100
0100
Low · default modelHow is this calculated?
CVSS score
5.7/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.36%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 10-06-2026
    PublishedVulnerability first disclosed.
  2. 10-06-2026
    Last modifiedVulnerability information updated.

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 cause data exfiltration through classic dashboards by redirecting a victim to an external site using a protocol-relative URL in a drill-down link.<br><br>The vulnerability exists because the URL classifier in classic dashboards only recognizes `http://` and `https://` schemes when checking for external URLs. Protocol-relative URLs such as `//attacker.com` bypass this check entirely, and Splunk Web does not show the external-navigation warning dialog to the victim.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.36%

Chance of exploitation in the next 30 days

Percentile

28%

Versus all other CVEs

30-day change

0.00 pp

From 0.36% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.36%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Splunk3 products
  • splunk≥ 9.3.0, < 9.3.13 | ≥ 9.4.0, < 9.4.12 | ≥ 10.0.0, < 10.0.7 | ≥ 10.2.0, < 10.2.4
  • splunk_cloud_platform≥ 9.3.2411, < 9.3.2411.132 | ≥ 10.1.2507, < 10.1.2507.23 | ≥ 10.2.2510, < 10.2.2510.15 | ≥ 10.3.2512, < 10.3.2512.13
  • splunk enterprise≥ 10.2, < 10.2.4 | ≥ 10.0, < 10.0.7 | ≥ 9.4, < 9.4.12 | ≥ 9.3, < 9.3.13

1 vendor · 3 products

References

1 links