CVE-2026-54353 in budibase
Summary
by MITRE • 06/27/2026
Budibase is an open-source low-code platform. Prior to 3.39.9, authenticated users with automation permissions can bypass Budibase's SSRF blacklist through DNS rebinding. The outbound fetch flow validates a hostname against the blacklist before the request is sent, but the actual socket connection later performs a separate DNS lookup through node-fetch. Since the validated IPs are never pinned to the connection, an attacker-controlled hostname can return a public IP during validation and a private/internal IP during the real connection. This results in a non-blind SSRF primitive against internal services reachable from the Budibase host, including loopback, RFC1918 ranges, and cloud metadata endpoints. This vulnerability is fixed in 3.39.9.
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Analysis
by VulDB Data Team • 06/27/2026
The vulnerability identified in Budibase versions prior to 3.39.9 represents a critical server-side request forgery flaw that exploits a fundamental weakness in the platform's outbound request validation mechanism. This issue affects authenticated users who possess automation permissions within the system, creating a significant attack surface that can be leveraged by malicious actors with limited access privileges. The vulnerability stems from a disconnect between the hostname validation process and the actual network connection establishment, creating a window where security controls can be bypassed through a sophisticated DNS rebinding technique. The SSRF protection mechanism in place only validates hostnames against a predefined blacklist during the initial validation phase but fails to maintain the resolved IP address binding throughout the complete request lifecycle.
The technical implementation of this vulnerability exploits a fundamental flaw in how node-fetch handles DNS resolution within the application's outbound communication flow. During the initial validation step, the system performs a hostname check against the configured blacklist, which appears to pass and allows the request to proceed. However, when the actual HTTP request is executed through node-fetch, the underlying library performs an independent DNS lookup that occurs after the initial validation has already completed. This separation between validation and connection establishment creates a race condition where an attacker can manipulate DNS responses to present different IP addresses during each phase of the process. The validated hostname resolves to a public IP address that passes the blacklist validation, but when node-fetch executes the actual connection, it performs a fresh DNS lookup that returns an internal/private IP address from the RFC1918 range or loopback interface.
This vulnerability enables attackers to perform non-blind server-side request forgery against internal services that are reachable from the Budibase host system, effectively bypassing traditional network segmentation controls. The attack surface includes access to localhost endpoints, private network services, and cloud metadata endpoints that are typically protected by network-level firewalls and security controls. This represents a significant escalation of privilege vulnerability since authenticated users who should only have limited automation capabilities can potentially access sensitive internal systems that would otherwise be isolated from external network access. The impact extends beyond simple data exfiltration to include potential reconnaissance of internal infrastructure, service enumeration, and access to privileged endpoints that may contain confidential information or administrative functions.
The security implications of this vulnerability align with CWE-918, which specifically addresses server-side request forgery vulnerabilities where applications fail to properly validate external requests. This flaw also corresponds to ATT&CK technique T1071.004 for application layer protocol usage and T1566 for phishing attacks that leverage compromised internal services. The DNS rebinding attack vector employed here demonstrates a sophisticated approach to bypassing security controls through timing-based manipulation of network resolution behavior. Organizations using Budibase versions prior to 3.39.9 should immediately implement mitigations including upgrading to the patched version, implementing additional outbound request filtering mechanisms, and monitoring for suspicious automation activity. Additional defensive measures should include network-level restrictions on outbound connections from the Budibase host and enhanced logging of external request patterns to detect potential exploitation attempts.
The root cause of this vulnerability highlights a common pattern in modern application security where assumptions about network behavior and DNS resolution can lead to security control bypasses. The issue demonstrates how seemingly robust validation mechanisms can be circumvented when network libraries perform independent operations that are not properly coordinated with existing security controls. This vulnerability serves as a reminder of the importance of maintaining consistent state throughout complex network operations and the necessity of validating all aspects of network communication, not just initial request parameters. The fix implemented in version 3.39.9 likely involves ensuring that DNS resolution results are consistently bound to the connection lifecycle or implementing more comprehensive validation that accounts for potential DNS rebinding scenarios.