Detect CVE-2026-20253: Splunk Enterprise Missing Authentication for Critical Function in IBM QRadar
Detects exploitation attempts targeting CVE-2026-20253, a missing authentication vulnerability (CWE-306) in Splunk Enterprise. This KEV-listed vulnerability allows unauthenticated access to critical Splunk functions. Attackers may leverage this to execute searches, exfiltrate data, or manipulate Splunk configurations without valid credentials.
MITRE ATT&CK
- Tactic
- Initial Access Persistence Collection
QRadar Detection Query
SELECT
sourceip,
destinationip,
destinationport,
URL,
username,
eventcount,
DATEFORMAT(starttime, 'YYYY-MM-dd HH:mm:ss') as event_time,
category,
logsourcename(logsourceid) as log_source
FROM events
WHERE
destinationport IN (8000, 8089, 9997, 8088)
AND (
URL ILIKE '%/services/search/jobs%'
OR URL ILIKE '%/services/data/inputs%'
OR URL ILIKE '%/services/admin%'
OR URL ILIKE '%/services/authentication%'
OR URL ILIKE '%/en-US/splunkd/__raw/services%'
)
AND (username IS NULL OR username = '' OR username = '-')
AND LOGSOURCETYPENAME(devicetype) IN ('Apache HTTP Server', 'IBM Security Network IPS (GX)', 'Palo Alto Networks Firewall', 'Check Point FireWall-1')
AND LAST 24 HOURS
GROUP BY sourceip, destinationip, URL
HAVING eventcount > 2
ORDER BY eventcount DESCQRadar AQL query identifying repeated unauthenticated connections to Splunk Enterprise ports and REST API paths, grouped by source and destination to surface scanning or exploitation activity.
Data Sources
Required Tables
False Positives & Tuning
- Network monitoring systems performing availability checks on Splunk ports
- Load balancers performing backend health checks without credentials
- Security scanners enumerating services during authorized penetration tests
- Splunk deployment server communications appearing as unauthenticated in some log sources
Other platforms for CVE-2026-20253
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Unauthenticated Splunk Search Job Creation via REST API
Expected signal: HTTP POST to port 8089 without Authorization header; Splunk web_access.log entry with null/anonymous user; network flow record to TCP/8089
- Test 2Unauthenticated Splunk User Enumeration via REST API
Expected signal: HTTP GET to /services/authentication/users on port 8089 without credentials; response body containing user list if vulnerable
- Test 3Unauthenticated Splunk Index Listing and Data Access
Expected signal: Sequential unauthenticated GET and POST requests to Splunk REST API; multiple different /services/ paths accessed from same source IP within short timeframe
- Test 4Unauthenticated Splunk Configuration Modification Attempt
Expected signal: HTTP POST to /services/data/inputs/ without Authorization header; Splunk audit log entry for configuration change with anonymous user context
References (4)
- https://advisory.splunk.com/advisories/SVD-2026-0603
- https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
- https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
- https://nvd.nist.gov/vuln/detail/CVE-2026-20253
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