CVE-2026-9186 PUBLISHED

Langflow is vulnerable to stored cross-site scripting and IP spoofing due to unsanitized Markdown rendering and untrusted proxy header trust

Assigner: ibm
Reserved: 21.05.2026 Published: 04.09.2026 Updated: 04.09.2026

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.).

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
CVSS Score: 6.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	Low	Integrity Impact	High
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	IBM
Product	Langflow OSS
Versions	affected from 1.0.0 to 1.11.2 (incl.)

Solutions

IBM strongly recommends addressing the vulnerability now by upgrading Langflow OSS to version 1.11.3 https://pypi.org/project/langflow/

Credits

odgrso GMO CyberSecurity by Ierae inc, Edward-x (YLChen-007) finder

References

https://www.ibm.com/support/pages/node/7285646

Problem Types

CWE-284 Improper Access Control CWE