# CVE-2026-116168: SiYuan before v3.8.7 Path Traversal Local File Read via MCP Asset Tool

Status: published. Published: 2026-10-25. Updated: 2026-11-04.

SiYuan before 3.8.7 contains a path traversal vulnerability in the MCP asset tool because validateAssetUploadPaths relies on an incomplete sensitive-path blacklist that omits .env and other secret files. Authenticated attackers driving the MCP asset upload action can copy such local files into the workspace and read them back via /assets/ over HTTP.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- siyuan-note / siyuan (github.com/siyuan-note/siyuan/kernel): ≥ 0; < 3.8.7 (affected, semver); 3.8.7 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.2 (medium); CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N; source: CNA: VulnCheck

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 6.2 (medium); CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.19% as of 2026-11-04; percentile 8.28%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-22

## Exploit evidence

- exploit: https://github.com/siyuan-note/siyuan/security/advisories/GHSA-q768-4j87-gf3w (ADP: CISA-ADP)

## References

- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-q768-4j87-gf3w (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/siyuan-before-3.8.7-path-traversal-local-file-read-via-mcp-asset-tool (CNA: VulnCheck; third-party-advisory)

- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-q768-4j87-gf3w (ADP: CISA-ADP; exploit)

- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-q768-4j87-gf3w (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/siyuan-before-3.8.7-path-traversal-local-file-read-via-mcp-asset-tool (disclosure@vulncheck.com)

- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-q768-4j87-gf3w (134c704f-9b21-4f2e-91b3-4a467353bcc0)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-116168; retrieved 2026-11-04; source updated 2026-11-04

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-116168; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-116168; retrieved 2026-11-04; source updated Not reported

Revision: 74a59e86e15ae8b7e760068732ba978bb60e57dbd0f2fcdf6cabb92a1db6ef8e

Canonical: https://y2.dev/cve/CVE-2026-116168

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.