CVE-2026-55450 is a critical-severity missing authentication for critical function vulnerability in langflow (pip), affecting versions < 1.9.1. It is fixed in 1.9.1.
Summary 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 adition, 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. Tested on commit 2d67402b1dbaefcbce85a244d4a6cd5e4bda1cfe Details Code is in langflow/api/v1/endpoints.py: As can be seen above, there is no authentication. There is not validation over flowid as well, unlike other endpoints: Function saveuploadedfile saves the file to local file-system. Suggested fix: Add authentication to route. Only return relative path or filename. PoC PoC: Example: Impact Space exhaustion on server that can lead to Denial-of-Service. Information leak - leakage of absolute path of langflow's cache directory in server. Patches Fixed in 1.9.1 via PR #12831. The deprecated POST /api/v1/upload/{flowid} endpoint now uses the getflow dependency, requiring an authenticated user and flow ownership (returns 404 for missing or cross-user flows), and enforces the maxfilesizeupload limit (HTTP 413), closing the unauthenticated upload and disk-exhaustion vectors. Upgrade to 1.9.1 or later. Note: the response still returns the file's absolute path (file_path); after this fix it is only disclosed to the authenticated owner of the flow. Ori Lahav Security Researcher @ Rubrik Inc.
A critical operation is accessible without requiring any authentication. Typical impact: any user can invoke the privileged function.
CVE-2026-55450 has a CVSS score of 9.3 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (1.9.1). Upgrading removes the vulnerable code path.
pip
langflow (< 1.9.1)langflow → 1.9.1 (pip)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Upgrade langflow to 1.9.1 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-55450 is a critical-severity missing authentication for critical function vulnerability in langflow (pip), affecting versions < 1.9.1. It is fixed in 1.9.1. A critical operation is accessible without requiring any authentication.
CVE-2026-55450 has a CVSS score of 9.3 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
langflow (pip) versions < 1.9.1 is affected.
Yes. CVE-2026-55450 is fixed in 1.9.1. Upgrade to this version or later.
Whether CVE-2026-55450 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade langflow to 1.9.1 or later.