by Kastro
Paper/Archive/CVE-2026-40518

CVE-2026-40518

bytedance deer-flow — ByteDance DeerFlow Path Traversal and Arbitrary File Write via Bootstrap Mode

EPSS 0.4%public exploitCVSS 9.1
critical.is priorityof 100
43
CVSS 9.1 (NVD)9.1 / 10 × 3027.3Not in CISA KEV+300.0EPSS percentile 29.3.293 × 205.9Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
deer-flow< 2176b2bbfccfce25ceee08318813f96d843a13fd2176b2bbfccfce25ceee08318813f96d843a13fdCNA

Scores by source

NVD9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
VulnCheck (CNA)7.1CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N
VulnCheck (CNA)7.1CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: partial

References

refgithub.com/bytedance/deer-flow/pull/2274patchgithub.com/bytedance/deer-flow/commit/2176b2bbfccfce25ceee08318813f96d843a13fdwriteupvulncheck.com/advisories/bytedance-deerflow-path-traversal-and-arbitrary-file-write-via-bootstrap-mode