CVE-2026-40518

Analyzed Analyzed - Analysis Complete

Path Traversal and Arbitrary File Write in ByteDance DeerFlow Agent

Publication date: 2026-04-17

Last updated on: 2026-06-05

Assigner: VulnCheck

Description

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.

CVSS Scores

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Meta Information

Published

2026-04-17

Last Modified

2026-06-05

Generated

2026-07-06

AI Q&A

2026-04-17

EPSS Evaluated

2026-07-05

NVD

CVE-2026-40518

EUVD

EUVD-2026-23456

Affected Vendors & Products

Vendor	Product	Version / Range
bytedance	deerflow	2.0-m0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-22	The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Attack-Flow Graph

Executive Summary

This vulnerability exists in ByteDance DeerFlow before commit 2176b2b and involves a path traversal and arbitrary file write issue during the bootstrap-mode custom-agent creation process.

The problem arises because the validation of the agent name can be bypassed, allowing attackers to supply traversal-style values or absolute paths as the agent name.

This manipulation influences directory creation and enables writing files outside the intended custom-agent directory.

As a result, attackers may achieve arbitrary file write on the system, subject to filesystem permissions.

Impact Analysis

This vulnerability can allow an attacker with limited privileges to write files anywhere on the filesystem where the application has write permissions.

Such arbitrary file write can lead to serious impacts including the possibility of executing malicious code, modifying or deleting important files, or disrupting system operations.

The overall impact depends on the filesystem permissions and the environment in which ByteDance DeerFlow is running.

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