Vulnerability · Published Apr 17, 2026 · Assigned by VulnCheck

CVE-2026-40518ByteDance DeerFlow Path Traversal and Arbitrary File Write via Bootstrap Mode

High 7.1

In plain English

A high-severity path traversal in deer-flow from bytedance. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities).

Severity (CVSS 3.1)7.1High

Exploit odds (30 days)0.4%top 70.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
bytedance	deer-flow	0 – before 2176b2bbfccfce25ceee08318813f96d843a13fd

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

References

https://github.com/bytedance/deer-flow/pull/2274 issue-tracking
https://github.com/bytedance/deer-flow/commit/2176b2bbfccfce25ceee08318813f96d843a13fd patch
https://www.vulncheck.com/advisories/bytedance-deerflow-path-traversal-and-arbitrary-file-write-via-bootstrap-mode third-party-advisory