CVE-2026-33228

Published Mar 20, 2026

Last updated 2 months ago

CVSS high 8.9
Splunk

Overview

Description
flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.
Source
security-advisories@github.com
NVD status
Modified
Products
flatted

Risk scores

CVSS 4.0

Type
Secondary
Base score
8.9
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
HIGH

CVSS 3.1

Type
Primary
Base score
9.8
Impact score
5.9
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity
CRITICAL

Weaknesses

security-advisories@github.com
CWE-1321
0b0ca135-0b70-47e7-9f44-1890c2a1c46c
CWE-915

Social media

Hype score
Not currently trending

Configurations

Related CVEs

  1. In Splunk MCP Server app versions below 1.2.1, a user who holds the "admin" Splunk role could execute arbitrary commands on the underlying operating system. The vulnerability is possible because of missing input validation in the app's credential management component, which deserializes stored data without checking whether the content is of the expected type.•CVE-2026-76404
  2. In Splunk On-Call (VictorOps) app versions below 1.0.43 on Splunkbase, a user who does not hold the "admin" or "power" Splunk roles could read a partially masked Application Programming Interface (API) key from the App Key Value Store (KV Store). The exposure is possible because the Splunk On-Call (VictorOps) app does not fully mask the API key before storing it in a KV Store collection that the user can read. For more information see About the app key value store (https://help.splunk.com/en/data-management/splunk-enterprise-admin-manual/9.2/administer-the-app-key-value-store/about-the-app-key-value-store) in the Splunk documentation.•CVE-2026-76405
  3. In Splunk Enterprise Security versions below 8.6.1, a user who holds the ess_analyst Splunk Enterprise Security role could change User and Entity Behavior Analytics (UEBA) search macros that scheduled searches run with administrator permissions, allowing for access to all relevant data and system integrity through those searches. The vulnerability is possible because the UEBA app metadata grants analyst roles write access to search macros that should be writable only by administrator roles. For more information see Users and roles for Splunk Enterprise Security (https://help.splunk.com/en/splunk-enterprise-security-8/install/8.4/installation/users-and-roles-for-splunk-enterprise-security) and Roles and knowledge objects in UEBA for Splunk Enterprise Security (https://help.splunk.com/en/splunk-enterprise-security-8/administer/8.5/user-and-entity-behavior-analytics/roles-and-knowledge-objects-in-ueba-for-splunk-enterprise-security) in the Splunk documentation.•CVE-2026-76388
  4. In Splunk Enterprise Security versions below 8.6.1, a user who holds a Splunk Enterprise Security role that contains the mc_investigation_read capability could inject Search Processing Language (SPL) through Analyst Queue search filters, allowing for access to all relevant data and system integrity available to the scheduled searches that run for that user. The vulnerability is possible because the Analyst Queue search filter handling does not validate filter field names before the fields are included in SPL searches. For more information see Users and roles for Splunk Enterprise Security (https://help.splunk.com/en/splunk-enterprise-security-8/install/8.4/installation/users-and-roles-for-splunk-enterprise-security), Manage analyst workflows using the analyst queue in Splunk Enterprise Security (https://help.splunk.com/en/splunk-enterprise-security-8/administer/8.4/mission-control/manage-analyst-workflows-using-the-analyst-queue-in-splunk-enterprise-security), and Overview of Mission Control in Splunk Enterprise Security (https://help.splunk.com/en/splunk-enterprise-security-8/user-guide/8.5/mission-control/overview-of-mission-control-in-splunk-enterprise-security) in the Splunk documentation.•CVE-2026-76387
  5. In Splunk SOAR versions below 8.6.0, an unauthenticated user could spoof the source IP address in a crafted request to an Automation Broker notification endpoint and execute arbitrary code on the Splunk SOAR host. The vulnerability is possible because the Splunk SOAR Automation Broker trusts a client-supplied source IP address header as proof that the request originates from the local system. Successful exploitation can expose all relevant data, affect system integrity, and disrupt service availability. For more information see About Splunk SOAR Automation Broker (https://help.splunk.com/en/splunk-soar/splunk-automation-broker/about-splunk-soar-automation-broker/about-splunk-soar-automation-broker) in the Splunk documentation.•CVE-2026-76356

References

Sources include official advisories and independent security research.