Is CVE-2026-40518 in the CISA KEV catalog?

No. CVE-2026-40518 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-40518?

CVE-2026-40518 has a CVSS v3 base score of 7.1 (HIGH).

What is the EPSS score for CVE-2026-40518?

CVE-2026-40518 has an EPSS score of 0.36% (27th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-40518

HIGH

7.1

CVSS v3

NVD

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.

CWE-22Path Traversal

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityLow

AvailabilityHigh

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H

Exploit Intelligence

0.36%probability of exploitation in 30 days

27thpercentile

Low risk: more likely to be exploited than 27% of all known CVEs.

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-05.