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InjectionWeakness · CWE-74

CVE-2026-6599

MEDIUM · 6.3 CVSS v3.1 Published 2026-04-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability was detected in langflow-ai langflow up to 1.8.3. The impacted element is the function get_client_ip/install_mcp_config of the file src/backend/base/langflow/api/v1/mcp_projects.py of the component Model Context Protocol Configuration API. Performing a manipulation of the argument X-Forwarded-For results in injection. The attack may be initiated remotely. The exploit is now public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A header injection vulnerability exists in langflow's MCP Configuration API where the get_client_ip function blindly trusts the X-Forwarded-For HTTP header without proper validation. Attackers can manipulate this header to inject malicious IP addresses, potentially enabling authentication bypass, IP spoofing, or log injection attacks.

MitigationImplement strict validation and sanitization of the X-Forwarded-For header, including IP address format validation and rejection of header values containing unexpected characters or multiple IP addresses. Consider not relying solely on this header for security-critical decisions.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify langflow installation and version
    Run 'pip show langflow' or check your package manager to determine the installed version of langflow. Compare this version against any known affected version ranges for CVE-2026-6599.
    Affected if A version of langflow is installed that contains the vulnerable get_client_ip function in the MCP Configuration API.
  2. Locate the get_client_ip function
    Search the langflow codebase for the get_client_ip function definition, typically in files related to MCP Configuration API or utilities handling HTTP request metadata.
    Affected if The get_client_ip function exists in the installed version and is being used by the application.
  3. Examine X-Forwarded-For header handling
    Inspect the get_client_ip function code to see how it retrieves and processes the X-Forwarded-For HTTP header. Look for any validation or sanitization logic applied to this header value.
    Affected if The function retrieves X-Forwarded-For without validating its contents, such as checking for valid IP address format or rejecting unexpected characters.
  4. Verify if multiple IP addresses are being processed
    Check whether the function handles multiple IP addresses in the X-Forwarded-For header (comma-separated values) without proper parsing or validation of each value.
    Affected if The function accepts or uses multiple IP addresses from the header without validating individual IP formats.
  5. Confirm the function is used in security-critical paths
    Determine if get_client_ip is called in contexts that affect authentication, authorization, access control, or log generation where the spoofed IP could be exploited.
    Affected if The vulnerable function is used for security decisions such as IP-based authentication, rate limiting, or access control logs.

You are affected if you are running a version of langflow containing the vulnerable get_client_ip function that processes the X-Forwarded-For header without validating its contents, and this function is used in your deployment for any security-related purpose.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement strict validation and sanitization of the X-Forwarded-For header, including IP address format validation and rejection of header values containing unexpected characters or multiple IP addresses. Consider not relying solely on this header for security-critical decisions.

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-6599 in production — separate from our analysis above.

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What this is

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