CVE-2026-19295 in Langflow OSS
Summary
by MITRE • 08/29/2026
IBM Langflow OSS 1.0.0 through 1.11.1 allows an authenticated attacker to execute arbitrary operating system commands in the server process by saving a flow with a crafted type field value and triggering a build of a wrapper flow that references it. This allowed privilege escalation from "authenticated flow user" to arbitrary OS-level command execution under the server process identity, bypassing the LANGFLOW_ALLOW_CUSTOM_COMPONENTS=false policy control.
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Analysis
by VulDB Data Team • 08/29/2026
The vulnerability identified in IBM Langflow versions 1.0.0 through 1.11.1 represents a critical security flaw that allows for remote code execution within the context of the application server process. This issue stems from an improper restriction on custom component handling, specifically involving how flow definitions are parsed and executed during the build phase. An attacker who has obtained valid authentication credentials to access the Langflow interface can exploit this weakness by crafting a specific type field value within a saved flow configuration. By subsequently triggering the building of a wrapper flow that references this crafted input, the application inadvertently executes arbitrary operating system commands on the host machine where the server is running.
The technical root cause lies in the insufficient validation and sanitization of user-supplied data when processing custom components or flow types. Although Langflow provides a configuration option known as LANGFLOW_ALLOW_CUSTOM_COMPONENTS which is intended to restrict users from loading untrusted code, this vulnerability effectively bypasses that control mechanism. The flaw allows an authenticated user to construct a payload that manipulates the internal execution engine into treating malicious input as executable system commands rather than safe data structures. This indicates a failure in implementing proper separation of logic and data, leading to command injection vulnerabilities within the backend processing pipeline.
From an operational impact perspective, this vulnerability results in complete compromise of the underlying server infrastructure for any authenticated user who can create flows. The attacker achieves privilege escalation from their standard application-level permissions to arbitrary operating system command execution under the identity of the Langflow server process. This level of access typically grants control over all files accessible by that service account, potential lateral movement within the network if the server has broader connectivity, and the ability to install persistent backdoors or exfiltrate sensitive data stored on the host system. The impact is severe because it undermines the fundamental security boundary between application users and the operating system kernel services.
This vulnerability aligns with Common Weakness Enumeration (CWE) categories such as CWE-78 Improper Neutralization of Special Elements used in an OS Command, commonly known as OS Command Injection, and CWE-269 Improvement of Privilege which describes the unauthorized elevation of privileges from a lower-level user to a higher-level system account. In terms of adversary tactics, this exploit maps to MITRE ATT&CK techniques including T1059 Command and Scripting Interpreter for executing commands via injected payloads and potentially T1078 Valid Accounts if the attacker leverages stolen or weak credentials to gain initial access before exploiting the command injection flaw.
To mitigate this risk, organizations running affected versions of IBM Langflow should immediately upgrade to a patched version where these input validation checks have been strengthened. Until an update is applied, administrators can enforce stricter network segmentation to limit the server's exposure and ensure that the LANGFLOW_ALLOW_CUSTOM_COMPONENTS setting remains strictly disabled if custom component functionality is not explicitly required for business operations. Additionally, implementing robust web application firewalls with specific rules against command injection patterns may provide a layer of defense in depth, although reliance on such controls alone is insufficient given the direct nature of this backend execution flaw. Regular auditing of authenticated user activities and flow configurations can also help detect anomalous behavior indicative of exploitation attempts.