---
id: CVE-2026-40518
title: ByteDance DeerFlow Path Traversal and Arbitrary File Write via Bootstrap Mode
summary: "ByteDance DeerFlow before commit\_2176b2b contains a path traversal and arbitrary file write vulnerability in bootstrap-mode custom-agent creation where the agent name validation is bypassed. Attackers can supply traversal-style values or…"
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H'
cvssSource: cna
cwe:
  - CWE-22
vendor: bytedance
product: deer-flow
affected:
  - deer-flow < 2176b2bbfccfce25ceee08318813f96d843a13fd
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-04-17T18:35:29.825676Z'
exploitAvailable: true
published: '2026-04-17'
updated: '2026-11-08'
sourceUpdated: '2026-11-08T14:02:56.489Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-40518'
references:
  - url: 'https://github.com/bytedance/deer-flow/pull/2274'
  - url: >-
      https://github.com/bytedance/deer-flow/commit/2176b2bbfccfce25ceee08318813f96d843a13fd
  - url: >-
      https://www.vulncheck.com/advisories/bytedance-deerflow-path-traversal-and-arbitrary-file-write-via-bootstrap-mode
tags:
  - cve.org
  - exploit-available
epss: 0.00356
epssPercentile: 0.29549
ingestedAt: '2026-11-08T14:51:22.440Z'
---

## Overview

ByteDance DeerFlow before commit 2176b2b contains a path traversal and arbitrary file write vulnerability in bootstrap-mode custom-agent creation where the agent name validation is bypassed. Attackers can supply traversal-style values or absolute paths as the agent name to influence directory creation and write files outside the intended custom-agent directory, potentially achieving arbitrary file write on the system subject to filesystem permissions.

## Affected

- `deer-flow < 2176b2bbfccfce25ceee08318813f96d843a13fd`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.