Code Injection in Langflow (CVE-2026-33017, CVSS 9.8, KEV)

Summary

Code injection in Langflow (CVE-2026-33017). Successful exploitation can lead to full system takeover. Exploitable via POST /api/v1/build_public_tmp/{flow_id}/flow. Listed in CISA KEV — actively exploited. Mitigation: upgrade to 1.9.0 or later.

Original description

The description as published by the source.

Langflow is a tool for building and deploying AI-powered agents and workflows. In versions prior to 1.9.0, the POST /api/v1/build_public_tmp/{flow_id}/flow endpoint allows building public flows without requiring authentication. When the optional data parameter is supplied, the endpoint uses attacker-controlled flow data (containing arbitrary Python code in node definitions) instead of the stored flow data from the database. This code is passed to exec() with zero sandboxing, resulting in unauthenticated remote code execution. This is distinct from CVE-2025-3248, which fixed /api/v1/validate/code by adding authentication. The build_public_tmp endpoint is designed to be unauthenticated (for public flows) but incorrectly accepts attacker-supplied flow data containing arbitrary executable code. This issue has been fixed in version 1.9.0.

Source: CISA Known Exploited Vulnerabilities NVD GitHub Advisory CISA KEV

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-2026-33017 has been found in Langflow.
Attackers can target a specific entry point like POST /api/v1/build_public_tmp/{flow_id}/flow over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 9.8/10.
Note: CISA has officially confirmed this is actively exploited in the wild. Treat it with elevated urgency.
What to do: upgrade Langflow to 1.9.0 or later.
If unsure, ask your IT team or search "Langflow CVE-2026-33017" on the vendor's site.

CVE-2026-33017 (Langflow) — CWE-94 / CVSS v3 9.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/v1/build_public_tmp/{flow_id}/flow / GET /api/v1/auto_login / POST /api/v1/flows/ / POST /api/v1/build_public_tmp/{id}/flow
Patched: 1.9.0 — apply immediately
Listed in CISA KEV — actively exploited, treat as top priority.
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 POST /api/v1/build_public_tmp/{flow_id}/flow without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Langflow. Attack surface: POST /api/v1/build_public_tmp/{flow_id}/flow / GET /api/v1/auto_login / POST /api/v1/flows/ / POST /api/v1/build_public_tmp/{id}/flow.

🔥 Severity

Severity: Critical (CVSS 9.8/10). Successful exploitation can lead to full system takeover. Listed in CISA KEV — actively exploited in the wild, treat as top priority.

🔧 How to fix

Update to 1.9.0.

🛡️ 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 POST /api/v1/build_public_tmp/{flow_id}/flow requests with malformed payloads or SQL meta-characters. Run grep -r 'langflow' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Related past incidents Similar incidents extracted from past CVEs

Drupalgeddon2

A similar vulnerability in the Drupal CMS (CVE-2018-7600) allowed remote code execution.

If this happens at your company Expected impact per business scenario

📌 E-commerce platform

Unauthorized access to backend systems could lead to data theft or alteration.

📌 Internal business systems

Could allow external parties to manipulate critical business workflows.

📌 Publicly accessible portals

May result in defacement or dissemination of false information.

Recommended action

Ensure immediate software updates and authenticate all changes within the application.

Response actions

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

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
Hunt for indicators of compromise detect
```
grep 'POST /api/v1/build_public_tmp/{flow_id}/flow' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'
```
アクセスログで POST /api/v1/build_public_tmp/{flow_id}/flow への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。
3
Consider incident declaration escalate
```
Notify SOC / on-call
```
CISA KEV登録済 = 実環境で悪用が観測されている。Step 2 で兆候があればインシデント対応宣言、無くてもパッチ適用までWAF強化を最優先で。
4
Apply patch patch
```
Upgrade Langflow to 1.9.0
```
ステージング環境で 1.9.0 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と、Step 2 で見つけた異常検知の続報チェックを含めること。
5
Post-deployment verification verify
```
Replay attack against POST /api/v1/build_public_tmp/{flow_id}/flow on staging to confirm patch closes the vector
```
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 Step 2 と同じログクエリ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":"1.9.0"}]}]

PyPI langflow

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.9.0"}]}]

References

advisory nvd.nist.gov
advisory github.com
advisory github.com
advisory sysdig.com
advisory github.com
package github.com
patch github.com
patch github.com
report medium.com
web cisa.gov
web github.com
web github.com
web cisa.gov
web github.com