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CVE-2026-51886 critical CVSS 9.8

Code Injection in langflow (CVE-2026-51886)

Summary

Code injection in langflow (CVE-2026-51886). Successful exploitation can lead to full system takeover. Exploitable via AUTO_LOGIN. Mitigation: upgrade to 1.10.1 or later.

Original description

The description as published by the source.

###Summary:
A critical Authenticated Remote Code Execution (RCE) vulnerability exists in the validate_code function of Langflow. The /api/v1/validate/code endpoint, meant to validate user-supplied code, leverages Python's exec() function. While it attempts to restrict execution to function definitions, it fails to account for decorators, which are evaluated at definition time. This allows any authenticated user to execute arbitrary code on the server, resulting in a full system compromise.

Details

The vulnerability is located in src/lfx/src/lfx/custom/validate.py(exposed via src/backend/base/langflow/api/v1/validate.py).

The validate_code function parses user input using ast. When it encounters a FunctionDef node, it compiles and executes it to check for extensive errors:

# src/lfx/src/lfx/custom/validate.py
if isinstance(node, ast.FunctionDef):
    code_obj = compile(ast.Module(body=[node], type_ignores=[]), "", "exec")
    # ...
    # exec_globals creates a restricted-looking scope, but standard builtins are available
    exec(code_obj, exec_globals)

By design, executing a function definition (def func(): ...) does not execute the function body. However, Python immediately evaluates decorators attached to the function definition. An attacker can supply a malicious decorator (e.g., a lambda or function call) to achieve immediate code execution during the "validation" phase.

Affected Versions

  • **/api/v1/validate/code had no authentication at al…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-51886 has been found in langflow.
Attackers can target a specific entry point like AUTO_LOGIN over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
What to do: upgrade langflow to 1.10.1 or later.
If unsure, ask your IT team or search "langflow CVE-2026-51886" on the vendor's site.

CVE-2026-51886 (langflow) — CWE-94 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: AUTO_LOGIN / e7c33dbaad / FunctionDef
Patched: 1.10.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

Arbitrary code execution (CWE-94) exists in langflow. Attackers reach the vulnerable code path via AUTO_LOGIN without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of langflow. Attack surface: AUTO_LOGIN / e7c33dbaad / FunctionDef.

🔥 Severity

Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 1.10.1.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'langflow' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'langflow' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で langflow を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade langflow to 1.10.1

    ステージング環境で 1.10.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

pip langflow
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.10.1"}]}]

References

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