---
schema: 1
kind: vulnerability
title: "CVE-2026-5027 — Langflow: unauthenticated path traversal to arbitrary file write, exploited in the wild"
headline: "CVE-2026-5027 — Langflow: unauthenticated path traversal to arbitrary file write, exploited in the wild"
summary: "Langflow CVE-2026-5027 (CVSS 8.8 path traversal → arbitrary file write) is being exploited in the wild, made effectively pre-auth by Langflow's default auto-login; ~7,000 instances are internet-exposed and a patch is now available (BleepingComputer, 2026-06-10)."
discovered_at: "2026-06-11T05:00:03Z"
event_date: 2026-06-10
run_id: 2026-06-11-7edf1d8a
priority: high
immediate_action: null
tags:
  - vulnerabilities
  - actively-exploited
  - pre-auth
  - path-traversal
  - rce
  - patch-available
regions:
  - global
sectors:
  - technology
entities: []
cves:
  - id: CVE-2026-5027
    cvss: "8.8"
    epss: null
    type: path-traversal
    vector: zero-click
    auth: pre-auth
    status:
      - exploited
      - patch-available
sources:
  - url: "https://www.bleepingcomputer.com/news/security/path-traversal-flaw-in-ai-dev-platform-langflow-exploited-in-attacks/"
    publisher: BleepingComputer
    role: primary
  - url: "https://www.tenable.com/security/research/tra-2026-26"
    publisher: Tenable TRA-2026-26
    role: corroborating
closed_sources: []
evidence:
  - quote: "CVE-2026-5027 (CVSS 8.8, CWE-22) is a path-traversal flaw in Langflow — the widely deployed open-source low-code platform for building LLM pipelines, RAG systems and agentic workflows."
    publisher: ctipilot v2 brief (migrated)
verification: multi-source
sourcing_note: "migration: evidence backfilled from v2 brief body (item predates the Evidence footer field)"
confidence: high
update_of: null
references: []
deep_dive: false
deep_dive_category: null
org_triage: null
watchlist_hit: false
actions:
  - "**Patch Langflow (1.9.0 / 1.10.0) and disable auto-login (CVE-2026-5027).** This pre-auth path-traversal-to-RCE is exploited in the wild with ~7,000 instances exposed. If patching is delayed, set `LANGFLOW_AUTO_LOGIN=false`, remove the instance from internet exposure, and hunt web logs for `POST /api/v2/files` requests containing `../` or `%2e%2e%2f`."
migrated_from: briefs/2026-06-11.md
---

CVE-2026-5027 (CVSS 8.8, CWE-22) is a path-traversal flaw in Langflow — the widely deployed open-source low-code platform for building LLM pipelines, RAG systems and agentic workflows. The `POST /api/v2/files` endpoint fails to sanitise the `filename` parameter in multipart form data, allowing `../` sequences to write files to arbitrary filesystem locations ([BleepingComputer, 2026-06-10](https://www.bleepingcomputer.com/news/security/path-traversal-flaw-in-ai-dev-platform-langflow-exploited-in-attacks/)). It is effectively pre-authentication: Langflow ships with `LANGFLOW_AUTO_LOGIN` enabled by default, so a single unauthenticated request obtains a valid session token before reaching the file-write primitive, which chains to code execution via webshell placement or `.pth` injection. Tenable discovered and disclosed the flaw on 27 March 2026 after two months of unsuccessful vendor contact ([Tenable TRA-2026-26, 2026-03-27](https://www.tenable.com/security/research/tra-2026-26)); VulnCheck subsequently observed active exploitation in honeypots, with attackers staging test files on victim systems, and Censys data shows roughly 7,000 publicly exposed instances. A patch is now available (Langflow 1.9.0 / langflow-base 0.8.3, with 1.10.0 released 10 June). Technique: `T1190` Exploit Public-Facing Application → `T1505.003` Web Shell.


#### CVE Summary Table

| CVE | Product | CVSS | EPSS | KEV | Exploited | Patch | Source |
|---|---|---|---|---|---|---|---|
| CVE-2026-5027 | Langflow (`POST /api/v2/files`) | 8.8 | n/a | No | Yes (VulnCheck) | 1.9.0 / 1.10.0 | [BleepingComputer](https://www.bleepingcomputer.com/news/security/path-traversal-flaw-in-ai-dev-platform-langflow-exploited-in-attacks/) |
| CVE-2026-41089 | Windows Netlogon (Server 2012–2025) | 9.8 | n/a | No | Yes (CCB Belgium) | May 2026 Patch Tuesday | [CERT-EU 2026-007](https://cert.europa.eu/publications/security-advisories/2026-007/) |

*CVE-2026-41089 is carried as a § 4 update — see below; it is listed here for the consolidated vulnerability view.*