CVE-2026-9186: CWE-284 Improper Access Control in IBM Langflow OSS
Description
IBM Langflow OSS versions 1.0.0 through 1.11.2 contain an improper access control vulnerability that allows remote authenticated attackers to bypass localhost-only restrictions by spoofing the X-Forwarded-For header. This enables arbitrary writes to IDE configuration files such as ~/.cursor/mcp.json. The vulnerability has a medium severity with a CVSS score of 6.5.
CVSS v3.1
Score 6.5medium
Affected software
IBM
Langflow OSS
cpe:2.3:a:ibm:langflow_oss:1.0.0:*:*:*:*:*:*:*cpe:2.3:a:ibm:langflow_oss:1.11.2:*:*:*:*:*:*:*Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-9186 is an improper access control vulnerability (CWE-284) in IBM Langflow OSS versions 1.0.0 through 1.11.2. Remote authenticated attackers can bypass the intended localhost-only restriction on MCP configuration installation by spoofing the X-Forwarded-For header to appear as 127.0.0.1. This bypass allows attackers to perform arbitrary writes to IDE configuration files, including ~/.cursor/mcp.json, potentially altering the IDE's behavior or configuration.
Potential Impact
The vulnerability allows remote authenticated attackers to bypass access controls intended to restrict MCP configuration installation to localhost. By spoofing the X-Forwarded-For header, attackers can write arbitrary data to critical IDE configuration files. This can lead to unauthorized modification of the IDE environment, potentially impacting integrity of the development environment. There is no indication of confidentiality or availability impact. No known exploits are reported in the wild.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict access to the Langflow OSS service to trusted users and networks, and monitor for suspicious header spoofing attempts. Avoid exposing the service to untrusted networks. Follow IBM's official guidance once published.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- ibm
- Date Reserved
- 2026-05-21T14:59:59.486Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a9ad7b6acd9273b49bb6365
Added to database: 09/04/2026, 14:37:42 UTC
Last enriched: 09/15/2026, 00:58:35 UTC
Last updated: 10/17/2026, 18:48:24 UTC
Views: 78
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