CVE-2026-9186Network attack vectorHinoki check available

Authenticated configuration-file writes via spoofed proxy header

Published Sep 4, 2026 · Updated Sep 4, 2026

Improper access control in IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated users to write IDE configuration files. The MCP configuration endpoint's client-IP helper treats an unverified X-Forwarded-For value of 127.0.0.1 as proof that a request is local. Any authenticated account that can reach the endpoint can bypass its localhost-only restriction and modify sensitive MCP files on the server.

CVSS severity6.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper access control in IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated users to write IDE configuration files. The MCP configuration endpoint's client-IP helper treats an unverified X-Forwarded-For value of 127.0.0.1 as proof that a request is local. Any authenticated account that can reach the endpoint can bypass its localhost-only restriction and modify sensitive MCP files on the server.

The record

CVE
CVE-2026-9186
Published
Sep 4, 2026
Updated
Sep 4, 2026
Vendor
IBM
Product
Langflow OSS
Classifications
CWE-284, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0 <=1.11.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

IBM · Langflow OSSversion=1.0.0 <=1.11.2

Published CVSS scores

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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo