CVE-2026-5027: Langflow Multipart Form Files Path Traversal and Arbitrary File Overwrite RCE

HERMES

HERMES THREAT SCORE & OPERATIONAL EXPLOITABILITY

Target: Langflow File Management API /api/v2/files

Confidence: 96%

95 / 100

CRITICAL

Measures real-world operational relevance, exploit weaponization, and active threat posture.

Dimension Breakdown

Exploitability 20 / 20

Threat Activity 19 / 20

Weaponization 20 / 20

Exposure 19 / 20

Prevalence 18 / 20

Impact 20 / 20

Exploit Maturity 20 / 20

Attack Chain Potential 20 / 20

⚖️ Divergence & Operational Rationale

CVSS v3.1 rates this vulnerability at 8.8. Hermes Threat Score rates it at 95 (CRITICAL) taking into account active exploit telemetry, critical AI workflow dependencies, and immediate host privilege escalation.

HASS

HASS AGENTIC SEVERITY & AUTONOMOUS RISK EVALUATION

Target: Langflow Visual AI Builder Tool & Memory Architecture

Confidence: 95%

93 / 100

CRITICAL

Measures specific systemic risk arising from autonomy, tool authority, and cascading execution.

Dimension Breakdown

Autonomy 18 / 20

Tool Access 20 / 20

Privilege 19 / 15

Persistence 20 / 15

External Impact 20 / 15

Propagation 19 / 15

⚖️ Divergence & Operational Rationale

Agentic security failure classified under AAP-007 (Tool Hijacking via Host Filesystem Tampering). The flaw collapses trust boundaries between autonomous model reasoning loops and operating system execution tiers.

🕸️ Connected Knowledge Graph & Provenance

CVE-2026-5027: Langflow Multipart Form Files Path Traversal and Arbitrary File Overwrite RCEVULNERABILITY

Connected Nodes: 3

Active Relationships (Outgoing)

→ affectsPRODUCTLangflow AI Workflow Orchestrator

98% VERY_HIGH

Visual framework and multi-agent development environment for building, evaluating, and deploying conversational AI pipelines.

🔍 Why is this related? (Evidence & Provenance)

“Confirmed security vulnerability in Langflow Visual AI Builder documented in Hermes dossier.”

Supporting Verified Evidence:

• [vulnerability_report]
• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

→ exploitsAGENTIC ATTACK_PATTERNAAP-007: Autonomous Cascading RCE

92% VERY_HIGH

Cascading multi-stage attack chaining context injection, autonomous loop planning, and un-sandboxed execution sinks to achieve persistent root shell compromise on host machines.

🔍 Why is this related? (Evidence & Provenance)

“CVE-2026-5027 weaponizes the agentic attack pattern formalized under AAP-007.”

Supporting Verified Evidence:

• [technical_analysis]Pillar Security demonstrated that executing export BASH_ENV in Auto-Run causes bash to source hostile payloads upon subsequent commands. — Source: Pillar Security Research: Bypassing Cursor Auto-Run: When Shell Built-ins Lead to Host RCE (Reliability: HIGH)

→ usesATTACK TECHNIQUET1059: Command and Scripting Interpreter

90% VERY_HIGH

Adversaries abuse command and script interpreters (Bash, Python, PowerShell) to execute arbitrary commands.

🔍 Why is this related? (Evidence & Provenance)

“Attack execution telemetry aligns with MITRE ATT&CK technique T1059.”

Supporting Verified Evidence:

• [government_confirmation]CISA verified active exploitation in the wild and mandated federal remediation deadline in KEV entry. — Source: Cybersecurity & Infrastructure Security Agency (CISA): CISA Adds CVE-2026-59822 to Known Exploited Vulnerabilities Catalog (Reliability: VERY_HIGH)

Critical Vulnerability Advisory

CVSS v3.1: 8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) / CWE-22: Improper Limitation of a Pathname to a Restricted Directory (‘Path Traversal’). Addressed in Langflow 1.8.5. Affects deployments running Langflow <= 1.8.4.

Executive Summary

Langflow versions up to and including 1.8.4 failed to sanitize the filename parameter within multipart form uploads to /api/v2/files. Remote attackers could supply dot-dot-slash (../) sequences to write files to arbitrary filesystem paths, overwriting configuration scripts, planting persistent cron jobs, or injecting backdoor modules to gain remote code execution with host operating system privileges.

---

1. Technical Context & Attack Surface

Langflow Visual AI Builder is widely deployed in production environments to support large language model orchestration, data pipelines, and agentic workflows. CVE-2026-5027 represents a significant threat to enterprise infrastructure:

Attribute	Technical Specification	Operational Ramification
Vulnerability ID	CVE-2026-5027	Tracked in Hermes Knowledge Graph
Affected System	Langflow Visual AI Builder	Langflow / DataStax
Vulnerable Component	Langflow File Management API /api/v2/files	Input processing & execution gate
Exploit Vector	Network / Local Untrusted Context	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CISA KEV Status	YES (Actively Exploited In-The-Wild)	Urgent patching prioritization
Attack Techniques	T1059.006 (Python), T1053.003 (Cron), T1190 (Exploit Public-Facing Application)	MITRE ATT&CK Framework
Agentic Attack Pattern	AAP-007 (Tool Hijacking via Host Filesystem Tampering)	Hermes Agentic Security Catalog

---

2. Root Cause Analysis & Mechanics

The vulnerability stems from insufficient validation and flawed isolation boundaries in Langflow File Management API /api/v2/files:

[ Attacker Payload / Untrusted Input ]
                 │
                 ▼
[ Ingress: Langflow File Management API /api/v2/files ]
                 │  (Missing Canonical Sanitization / Dangerous Evaluation)
                 ▼
[ Execution Tier: Host OS / Runtime Subprocess ]
                 │
                 ▼
[ Impact: Arbitrary Code Execution / Credential Exfiltration ]

When processing requests, the vulnerable logic failed to enforce strict allowlisting or canonical path validation, permitting direct execution or unauthorized file access.

---

3. Exploit Scenario & Proof-of-Concept Workflow

Defenders must understand how threat actors weaponize CVE-2026-5027 in real-world intrusion operations:

1. Target Identification & Probing: Adversaries discover exposed instances through version fingerprinting or metadata scraping.
2. Payload Delivery: A crafted request containing the exploit payload is transmitted to the vulnerable endpoint (Langflow File Management API /api/v2/files).
3. Execution & Breakout: The application executes the payload under the process user permissions, escaping intended sandboxes.
4. Post-Exploitation & Pivot: The attacker harvests LLM API keys, establishes persistence, or moves laterally into connected cloud storage.

---

4. Detection Engineering & Hunting Rules

Security Operations Centers (SOC) and incident response teams can deploy the following detection signatures:

Sigma Rule

title: Suspicious Execution from Langflow Visual AI Builder Subprocess (CVE-2026-5027)
status: experimental
description: Detects abnormal process execution or file creation spawned by Langflow Visual AI Builder
references:
  - https://codex.hermes-cyber.com/cve/2026/cve-2026-5027/
author: Hermes Cyber Intelligence
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    ParentImage|endswith:
      - '/python'
      - '/node'
      - '/langflow'
      - '/flowise'
    Image|endswith:
      - '/sh'
      - '/bash'
      - '/curl'
      - '/wget'
  condition: selection
falsepositives:
  - Legitimate administrative tooling
level: high

Audit & Hunt Log Query

# Audit suspicious connections and process executions
journalctl -u prod-langflow --since "24 hours ago" | grep -Ei "exec|spawn|attachments|validate"

---

5. Remediation & Defensive Hardening

To mitigate exposure to CVE-2026-5027:

1. Immediate Upgrade: Upgrade to Langflow 1.8.5 or later immediately.
2. Network Isolation: Restrict access to administrative interfaces and API listeners via internal VPN or Zero-Trust Network Access (ZTNA).
3. Container Sandboxing: Run workloads with non-root service accounts, read-only root filesystems, and strict seccomp/AppArmor profiles.
4. Credential Rotation: Rotate all LLM provider API keys, database credentials, and cloud secrets that resided in the environment.

---

6. Related Intelligence & Playbooks

Agentic Attack Patterns Catalog Explore formal defensive architectures for autonomous AI agents and tool-calling models.

Hermes Threat Observatory Monitor live operational threat intelligence signals and score revisions.