CVE-2026-56747: Cribl Stream RCE Vulnerability

CVE-2026-56747 Overview

CVE-2026-56747 is a code injection vulnerability [CWE-94] in the JSON Pointer-to-accessor compiler used by Cribl Stream. The flaw affects Cribl Stream versions before 4.18.2. A remote authenticated attacker with edit privileges can execute arbitrary JavaScript on the server by supplying a crafted database connection identifier or pack configuration value. The vulnerability stems from improper control of dynamically generated code during JSON Pointer compilation.

Critical Impact
Authenticated attackers with edit privileges can achieve arbitrary JavaScript execution on the Cribl Stream server, leading to full compromise of confidentiality, integrity, and availability of the data pipeline.

Affected Products

Cribl Stream versions prior to 4.18.2
Deployments exposing edit privileges to non-administrator users
Cribl Stream instances processing untrusted database connection identifiers or pack configurations

Discovery Timeline

2026-07-27 - CVE-2026-56747 published to NVD
2026-07-30 - Last updated in NVD database

Technical Details for CVE-2026-56747

Vulnerability Analysis

Cribl Stream uses a JSON Pointer-to-accessor compiler to translate pointer expressions into executable JavaScript accessor functions. The compiler does not properly sanitize input tokens before embedding them into the generated code. An attacker who can edit specific configuration fields, such as a database connection identifier or a pack configuration value, can inject JavaScript syntax into the compiled accessor. When the compiled function executes on the server, the injected payload runs with the privileges of the Cribl Stream process.

This class of flaw maps to [CWE-94] Improper Control of Generation of Code. Because the compiled output executes in the Node.js runtime hosting Cribl Stream, exploitation can pivot into arbitrary system commands, credential theft from environment variables, or tampering with data flowing through the observability pipeline.

Root Cause

The root cause is unsafe string concatenation or template composition inside the JSON Pointer-to-accessor compiler. User-supplied identifiers reach the code generator without proper escaping or allowlist validation, allowing pointer values to break out of their intended syntactic position and introduce arbitrary JavaScript statements.

Attack Vector

Exploitation requires network access to the Cribl Stream management interface and an authenticated account with edit privileges. The attacker submits a malicious database connection identifier or pack configuration value through the standard configuration API or UI. When the affected component compiles the JSON pointer accessor, the crafted payload is embedded into the generated function and executed server-side. See the Cribl Release Notes v4.18.2 and Cribl Security Notifications for vendor detail.

// No verified public exploit code is available for CVE-2026-56747.
// The vulnerability is triggered by placing JavaScript syntax
// inside a configuration value (database connection identifier
// or pack configuration) that the JSON Pointer-to-accessor
// compiler subsequently embeds into a generated function.

Detection Methods for CVE-2026-56747

Indicators of Compromise

Cribl Stream configuration entries with unusual characters, quotes, or JavaScript operators inside database connection identifiers or pack configuration values.
Unexpected outbound network connections initiated by the Cribl Stream Node.js process.
Spawned child processes such as sh, bash, or node -e originating from the Cribl Stream service account.
Audit log entries showing configuration edits followed by anomalous process activity on the host.

Detection Strategies

Review Cribl Stream audit logs for edits to database connection identifiers and pack configurations, focusing on non-alphanumeric payloads.
Correlate configuration changes with process execution telemetry on the underlying host to identify JavaScript-driven command execution.
Deploy endpoint detection and response tooling on Cribl Stream hosts to flag suspicious child processes from the cribl service account.

Monitoring Recommendations

Enable verbose audit logging for the Cribl Stream configuration API and forward logs to a SIEM for retention and correlation.
Alert on any configuration values containing characters such as `, ${, );, or require( in identifier fields.
Baseline expected outbound connections from the Cribl Stream host and alert on deviations.

How to Mitigate CVE-2026-56747

Immediate Actions Required

Upgrade Cribl Stream to version 4.18.2 or later on all Leader and Worker nodes.
Audit the list of users with edit privileges and remove access from any account that does not require it.
Rotate credentials and secrets accessible to the Cribl Stream process if unauthorized configuration edits are found.

Patch Information

Cribl addressed CVE-2026-56747 in Cribl Stream 4.18.2. Refer to the Cribl Release Notes v4.18.2 security fixes section and the Cribl Security Notifications portal for the authoritative advisory and download links.

Workarounds

Restrict edit privileges to a minimal set of trusted administrators until the patch is applied.
Place the Cribl Stream management interface behind a VPN or IP allowlist to reduce exposure of authenticated endpoints.
Run Cribl Stream under a dedicated, least-privileged service account with no interactive shell and limited filesystem access.

bash

# Verify installed Cribl Stream version and confirm patched build
/opt/cribl/bin/cribl version
# Expected output should show 4.18.2 or later