critical CVSS 9.9

CVE-2026-9135·Python vulnerability

IBM Langflow OSS 1.0.0 through 1.10.0 Langflow versions up to 1.9.2 (commit 94981c443d4918517b9e8163d70fc598dc33a32d) contain a code injection vulnerability in the Policies component's ToolGuard integration that bypasses the allow_custom_components=false security control. The vulnerability exists because the validation mechanism only checks the main component source code in node_template["code"]["value"] but fails to validate dynamic CodeInput fields that store generated ToolGuard Python files. Attackers can embed malicious Python code in these unvalidated dynamic fields, which are persisted in Flow.data and later executed server-side when a guarded tool is invoked through the ToolGuard runtime. This allows authenticated users with flow creation privileges to achieve arbitrary Python code execution on the backend despite custom component restrictions. The vulnerability can be escalated through cross-tenant flow manipulation via the agentic MCP update_flow_component_field tool, which accepts attacker-controlled user_id parameters, enabling attackers to inject malicious code into victim users' flows. When combined with publicly accessible flows and specific misconfigurations (AUTO_LOGIN=true, NEW_USER_IS_ACTIVE=true), the attack can be conducted with reduced authentication requirements.

Severity
critical
Software
Python
Fixed in
1.10.1
Published
2026-07-17

Affected versions

From: 1.0.0

Until: 1.10.1

Fixed in: 1.10.1

How to fix this CVE

Upgrade IBM Langflow OSS to version 1.10.1 or later to patch the code injection vulnerability in the ToolGuard component. Organizations running versions 1.0.0 through 1.10.0 should prioritize this update immediately, as the vulnerability allows authenticated users to execute arbitrary Python code on the backend by bypassing custom component restrictions. Verify that the allow_custom_components security control is properly enforced after applying the patch.

sudo dnf update python3-langflow

Defensia detects this vulnerability

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement request filtering to block or flag flow creation and modification requests that contain suspicious CodeInput field payloads containing Python keywords (exec, __import__, subprocess, os.system, eval). Monitor for cross-tenant flow manipulation attempts via the update_flow_component_field endpoint by validating that the user_id parameter matches the authenticated session user.

How to check if you are affected

  1. Check installed Langflow version: pip show langflow | grep Version
  2. Verify allow_custom_components setting in your Langflow configuration file (typically config.yaml or environment variables): grep -i allow_custom_components /path/to/langflow/config.yaml
  3. Search server logs for suspicious CodeInput field modifications or ToolGuard runtime executions: grep -i 'ToolGuard\|CodeInput\|code_injection' /var/log/langflow/*.log
  4. Confirm patch installation by checking Langflow version is 1.10.1 or higher: pip show langflow | grep Version

FAQ

What is CVE-2026-9135?

CVE-2026-9135 is a critical code injection vulnerability in IBM Langflow OSS that allows authenticated users to embed malicious Python code in unvalidated dynamic CodeInput fields within the ToolGuard component, bypassing the allow_custom_components=false security control and achieving arbitrary code execution on the backend.

Is CVE-2026-9135 being actively exploited?

No, according to CISA KEV data, CVE-2026-9135 is not currently being actively exploited in the wild, and no public exploits are available. However, the vulnerability has a critical CVSS score of 9.9 and should be patched immediately.

What versions of Langflow are affected by CVE-2026-9135?

Langflow versions 1.0.0 through 1.10.0 are vulnerable. Version 1.10.1 and later contain the security patch.

How do I check if my server is vulnerable to CVE-2026-9135?

Run 'pip show langflow' and check the Version field. If it shows 1.10.0 or earlier, your installation is vulnerable. Additionally, verify that allow_custom_components is set to false in your configuration with 'grep -i allow_custom_components /path/to/config.yaml'.

Does Defensia detect CVE-2026-9135?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Langflow is installed on a monitored server, CVE-2026-9135 will appear in your dashboard with remediation steps.

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References

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