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critical·Product Based Web Vulnerabilities·Updated Jul 31, 2026

CVE-2026-55450 Scanner

CVE-2026-55450 Scanner - Unrestricted File Upload vulnerability in Langflow

Est. Time~10 seconds
Scan TypeGroup Scan
Targetsurl
CostFree
0
Times Used
by S4E users
0
Assets Scanned
domains & IPs
0
Vulnerabilities Found
confirmed findings
References
CVECVE-2026-55450
9.3
CVSScritical
Exploitable remotely over the internet · no authentication required.

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.1, unauthenticated users can upload any amount of data to the server without any limitations. No need for any prior knowledge, only network access to Langflow. This can lead to space exhaustion on the server. In addition, in the response, the absolute path of the uploaded file is reported to the attacker, which is an information leak that can assist in chaining other primitives. This vulnerability is fixed in 1.9.1.

Attack Vector
Network
Privileges Req.
None
User Interaction
None
Affected
langflowby langflow-ai
< 1.9.1
Updated Aug 19, 2026View on NVD →
Detail

Langflow is a software application used for managing and visualizing workflows in various environments. It is widely used by developers and engineers to streamline processes and improve productivity. The platform provides users with an interface to automate repetitive tasks and integrate different tools and services. Additionally, Langflow supports collaborative project management, making it easier for teams to coordinate and execute tasks efficiently. The system is popular in industries that require process optimization and data integration. Langflow enjoys a strong user base due to its flexibility and comprehensive feature set.

The vulnerability in question is an unrestricted file upload issue within Langflow versions prior to 1.9.1. It allows unauthenticated attackers to upload potentially malicious files without limitations, posing significant risks. This vulnerability can lead to server storage exhaustion and unintended exposure of file paths. Exploiting this flaw can provide attackers with information that may assist in further malicious activities. The lack of controls on file uploads makes the system susceptible to misuse by unauthorized users. Addressing this vulnerability is crucial to maintaining the security and integrity of affected systems.

The technical details of this vulnerability involve the endpoint {{BaseURL}}/api/v1/upload/11111111-1111-1111-1111-111111111111, which does not have adequate limitations on file uploads. Attackers can use this endpoint to upload files with excessively long filenames, leading to errors such as "[Errno 36] File name too long". The lack of authentication requirements for accessing the upload functionality further exacerbates the problem. The vulnerability is detectable when a POST request with a specifically crafted multipart/form-data body results in a server error. This unrestricted access makes the endpoint a prime target for exploitation.

When exploited, the unrestricted file upload vulnerability can have several adverse effects. Malicious attackers might exploit the vulnerability to fill server storage, leading to potential downtime or degraded performance. Additionally, the exposure of file paths can provide attackers with sensitive information, aiding subsequent attacks. In severe cases, arbitrary code execution could be achieved if the uploaded files are executed on the server. Therefore, the vulnerability poses a substantial risk to affected systems, underscoring the importance of prompt patching. System administrators must remain vigilant to prevent unauthorized access and potential data compromise.

REFERENCES

Solution Advice
Remediation:
  • Update Langflow to version 1.9.1 or later to patch the vulnerability.
  • Implement strict file type validation and size restrictions on file uploads.
  • Use authentication mechanisms to limit access to the file upload function.
  • Regularly audit and monitor server storage for unusual activity.
  • Employ security measures such as web application firewalls to detect and block malicious file uploads.

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