CVE-2026-18891 in Langflow OSS
Summary
by MITRE • 08/29/2026
IBM Langflow OSS 1.0.0 through 1.11.1 could allow a remote attacker to execute arbitrary flows and access sensitive information due to improper authentication.
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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 stemming from insufficient authentication controls within the application's architecture. As an open-source framework designed for building large language model applications, Langflow relies on robust access control mechanisms to ensure that only authorized users can interact with its components and data stores. In this specific instance, the improper implementation of authentication protocols allows remote attackers to bypass security checks entirely. This failure in identity verification means that unauthenticated entities can gain direct entry into the system without providing valid credentials or tokens, effectively rendering the application's perimeter defenses obsolete for any user attempting to access protected resources remotely.
The technical nature of this flaw involves a breakdown in how session management and request validation are handled by the server-side components. When an attacker sends requests to the Langflow interface, the application fails to adequately verify the authenticity or authorization level of the caller before processing sensitive operations. This lack of rigorous input validation regarding user identity creates a pathway for unauthorized access. The vulnerability is not limited to simple information disclosure; it extends to the execution capabilities of the platform itself. Because Langflow allows users to define and run flows that may involve complex logic, data retrieval, or external API calls, an attacker who bypasses authentication can manipulate these workflows to perform actions intended only for legitimate administrators or end-users.
The operational impact of this vulnerability is severe due to the potential for arbitrary code execution and significant data compromise. An adversary exploiting this flaw could execute malicious flows that interact with underlying systems, potentially leading to remote code execution on the host infrastructure if the flow logic invokes unsafe functions or system commands. Furthermore, the ability to access sensitive information implies that confidential datasets processed by the Langflow instances, such as proprietary business intelligence, personal identifiable information, or intellectual property, are exposed to unauthorized parties. This dual threat of data exfiltration and system compromise undermines the integrity, confidentiality, and availability principles central to cybersecurity frameworks. The attacker does not need physical access or prior insider knowledge beyond the network address of the vulnerable instance, making this a high-risk vector for widespread exploitation in environments where Langflow is deployed without additional protective layers.
From an industry standard perspective, this vulnerability aligns with CWE-287, which describes Improper Authentication, and CWE-306, Missing Authentication for Critical Function. The ability to execute arbitrary flows places it within the realm of CWE-94, Improper Control of Generation of Code or Script, particularly when those scripts interact with system resources. In terms of offensive security tactics, this aligns with MITRE ATT&CK techniques related to Initial Access via valid accounts and potentially Command and Scripting Interpreter if the executed flows result in shell access or script execution on the backend servers. The lack of proper session validation also touches upon CWE-613, Insufficient Session Expiration, although the primary issue is the complete absence of required authentication rather than just weak expiration policies.
Mitigation strategies must focus immediately on restricting network exposure and applying vendor-provided patches. Organizations running Langflow versions 1.0.0 through 1.11.1 should upgrade to a patched version where these authentication checks have been rigorously implemented by the development team. Until an update is applied, it is imperative to place the application behind a reverse proxy or web application firewall that enforces strict access control lists and validates incoming requests against known malicious patterns. Additionally, implementing network segmentation can limit lateral movement if an attacker successfully exploits this vulnerability. Security teams should also audit existing deployments for any signs of unauthorized flow execution or unusual data egress traffic, as these may indicate active exploitation attempts. Regular security assessments and penetration testing are recommended to verify that authentication controls remain robust against evolving attack vectors.