CVE-2026-27702: Budibase RCE Vulnerability

CVE-2026-27702 Overview

CVE-2026-27702 is a critical Remote Code Execution (RCE) vulnerability affecting Budibase, a popular low-code platform used for creating internal tools, workflows, and admin panels. The vulnerability stems from an unsafe eval() implementation in Budibase's view filtering functionality, allowing any authenticated user—including those on free tier accounts—to execute arbitrary JavaScript code on the server.

Critical Impact

Authenticated attackers can achieve full server-side code execution, extract sensitive environment variables including API keys, JWT secrets, CouchDB admin credentials, and AWS keys, potentially compromising the entire Budibase Cloud infrastructure and gaining access to tenant databases.

Affected Products

• Budibase Cloud (SaaS) versions prior to 3.30.4
• Self-hosted deployments are NOT affected (they use native CouchDB views)

Discovery Timeline

• 2026-02-25 - CVE-2026-27702 published to NVD
• 2026-02-25 - Last updated in NVD database

Technical Details for CVE-2026-27702

Vulnerability Analysis

This vulnerability represents a severe Code Injection flaw (CWE-20: Improper Input Validation) where user-controlled view map functions are directly passed to JavaScript's eval() function without any sanitization or validation. The vulnerable code resides in packages/server/src/db/inMemoryView.ts, a component specific to Budibase's cloud deployment architecture.

The attack is particularly dangerous because the app-service pod runs with critical secrets baked into its environment variables. Successful exploitation allows attackers to extract INTERNAL_API_KEY, JWT_SECRET, CouchDB admin credentials, AWS keys, and other sensitive configuration data. Security researchers verified that using extracted CouchDB credentials, they could achieve direct database access, enumerate all tenant databases, and confirm that user records including email addresses are readable across the platform.

Root Cause

The root cause is the direct evaluation of user-supplied view map functions without proper input sanitization. The vulnerable code path in packages/server/src/db/inMemoryView.ts accepts user-controlled strings and passes them directly to eval(), a well-known dangerous practice that enables arbitrary code execution. This implementation was specific to the cloud deployment model's in-memory view system, which is why self-hosted installations using native CouchDB views remain unaffected.

Attack Vector

The attack is network-accessible and requires only low-privilege authentication (free tier account access). An attacker can craft malicious view filter expressions that, when processed by the vulnerable eval() call, execute arbitrary JavaScript code within the server's Node.js runtime context. This provides access to the process environment, file system, and network capabilities of the application container.

The security patch introduces proper input validation through token mapping and safe expression building:

function tokenOrThrow(type: "condition" | "conjunction", token?: string) {
  const mappedToken = token ? TOKEN_MAP[token] : undefined
  if (!mappedToken) {
    throw new Error(`Invalid filter ${type}: ${token}`)
  }
  return mappedToken
}

function docKeyExpression(key: string) {
  return `doc[${JSON.stringify(key)}]`
}

function isEmptyExpression(key: string) {
  const docExpression = docKeyExpression(key)
  return `(
      ${docExpression} === undefined ||
      ${docExpression} === null ||
      ${docExpression} === "" ||
      (Array.isArray(${docExpression}) && ${docExpression}.length === 0)
  )`
}

Source: GitHub Commit Update

Detection Methods for CVE-2026-27702

Indicators of Compromise

• Unusual view filter requests containing JavaScript code patterns such as process.env, require(), or eval()
• Unexpected access to environment variables or attempts to read /proc/self/environ
• Anomalous CouchDB queries originating from the app-service pod
• Access logs showing enumeration of tenant databases
• Outbound network connections from the Budibase application container to unexpected destinations

Detection Strategies

• Monitor application logs for view filtering operations containing suspicious JavaScript syntax or code injection patterns
• Implement runtime application self-protection (RASP) to detect eval() calls with untrusted input
• Review CouchDB access logs for unauthorized database enumeration or cross-tenant data access attempts
• Deploy network monitoring to detect data exfiltration attempts from Budibase containers

Monitoring Recommendations

• Enable detailed logging for all view creation and filtering operations in Budibase
• Set up alerts for any access to sensitive environment variables from application code paths
• Monitor for unusual authentication patterns, especially free-tier accounts accessing view filtering functionality
• Implement anomaly detection on CouchDB query patterns to identify unauthorized tenant database access

How to Mitigate CVE-2026-27702

Immediate Actions Required

• Upgrade Budibase Cloud deployments to version 3.30.4 or later immediately
• Rotate all sensitive credentials including INTERNAL_API_KEY, JWT_SECRET, CouchDB admin credentials, and AWS keys
• Review access logs to determine if the vulnerability was exploited prior to patching
• Audit tenant databases for signs of unauthorized access or data exfiltration

Patch Information

Budibase has released version 3.30.4 which addresses this vulnerability. The fix implements proper input validation through a token mapping system that rejects invalid filter conditions and conjunctions, along with safe document key expression building using JSON.stringify() to prevent injection attacks.

For detailed patch information, refer to:

• GitHub Security Advisory GHSA-rvhr-26g4-p2r8
• GitHub Release 3.30.4
• GitHub Pull Request Discussion

Workarounds

• Self-hosted Budibase deployments are not vulnerable as they use native CouchDB views instead of the in-memory view implementation
• For Budibase Cloud users, there is no workaround other than waiting for the vendor-managed update or temporarily restricting access to view filtering functionality
• Implement network-level restrictions to limit outbound connectivity from Budibase containers
• Consider implementing Web Application Firewall (WAF) rules to detect and block suspicious view filter payloads containing JavaScript code patterns

# Verify Budibase version after update
budibase --version
# Expected output: 3.30.4 or later

# Review environment for exposed secrets that need rotation
env | grep -E "(API_KEY|JWT_SECRET|COUCH|AWS)"