6.5Medium
Langflow Langflow
CVE-2026-9186
IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated attackers to bypass localhost-only MCP configuration installation by spoofing X-Forwarded-For: 127.0.0.1 header, enabling arbitrary writes to IDE config files (~/.cursor/mcp.json, etc.).
What this means for your business
- It affects Langflow. It matters if your company, or a supplier that handles your data, runs it.
- An attacker can use it remotely, over a network, with an ordinary user login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.3% chance of attack attempts being seen in the next 30 days, ranking above 19% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Langflow, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 6.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N- Weakness
- CWE-284
- Assigned by
- psirt@us.ibm.com
Dates
- Published
- 2026-09-04
- Last modified
- 2026-09-08
- Sources
- NVD
Affected products
- Langflow Langflow1.0.0 - 1.11.3
- Apple Macosall versions
- Linux Linux Kernelall versions
- Microsoft Windowsall versions
As listed in the NVD configuration data. Not a statement about your estate.