# CVE-2026-40518

> Vulnerability · severity: **HIGH** (CVSS 7.1).

## 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.

## Key facts

- **CVE ID:** CVE-2026-40518
- **Published:** 2026-04-17
- **CVSS severity:** HIGH
- **CVSS base score:** 7.1
- **CWE codes:** CWE-22

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40518

## Citation

> AI Analytics. CVE-2026-40518. Retrieved 2026-07-20 from https://api.ai-analytics.org/cve/CVE-2026-40518. Derived from NIST NVD. Licensed CC0.

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