CVE-2026-19875 in Langflow OSS
Summary
by MITRE • 08/19/2026
IBM Langflow OSS 1.0.0 through 1.10.0 could allow a remote attacker to overwrite administrator email information and abuse the server as an outbound relay due to missing authentication for the registration endpoint.
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Analysis
by VulDB Data Team • 08/19/2026
The vulnerability identified in IBM Langflow versions 1.0.0 through 1.10.0 represents a critical failure in access control mechanisms, specifically within the user registration subsystem of the application. This flaw stems from the absence of mandatory authentication checks on the API endpoint responsible for handling new user registrations and administrative configuration updates. In a properly secured web application, endpoints that modify privileged settings or create administrator accounts must verify the identity and permissions of the requesting entity before processing any state-changing requests. The lack of such verification allows unauthenticated actors to interact directly with these sensitive functions over the network without providing valid credentials or session tokens. This type of misconfiguration is a classic example of broken access control, where the server fails to enforce appropriate restrictions on unauthorized actions that are intended for privileged users only.
The technical exploitation of this vulnerability enables an attacker to perform several malicious activities by interacting with the unprotected registration endpoint. By sending crafted HTTP requests, a remote adversary can overwrite existing administrator email addresses or inject new administrative accounts into the system. This capability effectively allows the attacker to hijack administrative privileges or disrupt the operational integrity of the platform by altering critical configuration data. Furthermore, because Langflow is often deployed as an AI orchestration tool that may handle sensitive workflows and integrations with external services, compromising the administrator account provides a foothold for deeper intrusion into the underlying infrastructure. The ability to modify email settings can also facilitate phishing attacks or credential stuffing campaigns against other users within the organization by altering notification pathways or reset links associated with administrative accounts.
Beyond direct privilege escalation, this vulnerability introduces significant risks related to abuse of system resources and reputation damage. An attacker who gains control over administrator configurations may manipulate outbound communication channels, potentially turning the Langflow server into an open relay for spam or malicious payloads. This misuse can lead to IP address blacklisting by email providers, causing legitimate organizational emails to be flagged as junk or rejected entirely. Additionally, if the application is integrated with external AI models or data sources, compromising administrative access could allow the attacker to inject malicious prompts or alter workflow logic, leading to unauthorized data exfiltration or manipulation of AI-generated outputs. The operational impact extends beyond immediate security breaches to include potential regulatory non-compliance and loss of trust among users who rely on the integrity of the platform's administration and communication systems.
To mitigate this vulnerability, organizations running IBM Langflow versions 1.0.0 through 1.10.0 should immediately upgrade to a patched version where proper authentication controls have been implemented for all administrative endpoints. Until an update is applied, network-level mitigations such as restricting access to the registration API via firewall rules or reverse proxy configurations can provide temporary relief by limiting exposure to trusted internal networks only. It is also advisable to audit existing user accounts and email configurations for any unauthorized changes that may have occurred during periods of vulnerability exploitation. Implementing robust identity and access management practices, including multi-factor authentication for administrative roles and regular security assessments aligned with industry standards like CWE-284 (Improper Access Control) and MITRE ATT&CK techniques related to account manipulation such as T1098 (Account Manipulation), will help prevent similar incidents in the future. Regular monitoring of access logs for anomalous registration attempts can further enhance detection capabilities and reduce the window of exposure for this class of vulnerabilities.