Langflow: IP Spoofing Bypass via `X-Forwarded-For` Allowing Remote Configuration Write

published 2026-10-05 34 d ago modified 2026-10-15 24 d ago also GHSA-4f6c-2vvp-gw82 , PYSEC-2026-4229 , EUVD-2026-92800

cvss: 7.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

Langflow is a tool for building and deploying AI-powered agents and workflows. From 1.5.0 until 1.10.3, an IP spoofing vulnerability in the Model Context Protocol (MCP) configuration installation endpoint (POST /api/v1/mcp/project/{project_id}/install) allowed authenticated remote attackers to bypass the "local-only" access restriction. By sending a spoofed X-Forwarded-For: 127.0.0.1 header, an attacker could make the server treat the request as originating from localhost, letting them write/overwrite an MCP client configuration file on the server's filesystem. This vulnerability is fixed in 1.10.3.

Patch / fix

fixed in 1 links 4

pypi langflow 1.10.3

github.com/langflow-ai/langflow@1f39a4b commit
github.com/langflow-ai/langflow@94859df commit
github.com/langflow-ai/langflow#13915 pull request
github.com/langflow-ai/langflow/releases/tag/v1.10.3 release

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 33 d ago (2026-10-06)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/langflow-ai/langflow/security/advisories/GHSA-4f6c-2vvp-gw82 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
OSV	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
GitHub	3.1	7.1	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L

Affected packages

ecosystem	package	affected	fixed in
pypi	langflow	>=1.5.0, <1.10.3	1.10.3

Affected products

langflow-ai langflow

Classification

Weakness

CWE-290 Authentication Bypass by Spoofing
CWE-345 Insufficient Verification of Data Authenticity

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary