What’s Vulnerable › Vulnerabilities

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

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-17 · updated 2026-10-26
• Weakness: CWE-22

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

• ByteDance Deerflow: 2.0-m0

References

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

Get alerted when CVE-2026-40518 or the next vulnerability affects your stack