Detect Prototype Pollution in @deepstream/server (CVE-2026-49252) in Splunk
CVE-2026-49252 is a critical prototype pollution vulnerability (CVSS 9.9) in @deepstream/server versions prior to 10.0.5. An attacker can manipulate JavaScript object prototypes via crafted deepstream messages, potentially leading to remote code execution, privilege escalation, or denial of service within the Node.js server process.
MITRE ATT&CK
SPL Detection Query
index=* sourcetype IN ("node:app", "syslog", "auditd", "WinEventLog:Security")
| eval suspicious_proto = if(match(_raw, "(__proto__|\\[\"constructor\"\\]|Object\.prototype)"), 1, 0)
| eval deepstream_proc = if(match(process, "deepstream") OR match(command, "deepstream"), 1, 0)
| where deepstream_proc=1 OR (suspicious_proto=1 AND (match(source, "deepstream") OR match(_raw, "deepstream")))
| stats count by host, source, process, command, suspicious_proto, _time
| sort -_time
| table _time, host, source, process, command, suspicious_proto, countSearches application and system logs for deepstream server processes and prototype pollution payload patterns (__proto__, constructor, Object.prototype) in raw log data.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate JavaScript application logs that reference prototype in debug output
- Node.js framework logs from non-deepstream packages that surface prototype terminology
- Automated dependency auditing tools generating log entries mentioning prototype pollution
Other platforms for CVE-2026-49252
Testing Methodology
Validate this detection against 3 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 1Deepstream Prototype Pollution via Crafted Client Message
Expected signal: Node.js application logs should show receipt of a record set message with __proto__ key; process monitoring may show unexpected property on Object.prototype after message processing
- Test 2deepstream Server Version Enumeration
Expected signal: Process execution event for node reading package.json; stdout output containing version string below 10.0.5 confirms vulnerability
- Test 3Prototype Pollution Object Property Verification
Expected signal: Node.js process execution with inline script; stdout output 'YES - VULNERABLE' confirms Object.prototype susceptibility
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