PatchSiren

PatchSiren cyber security CVE debrief

CVE-2026-74798 SiYuan CVE debrief

The CVE record for CVE-2026-74798 was published on 2026-08-17T11:16:39.873Z and has not been modified since then. The vulnerability affects SiYuan kernel versions before v3.7.4 and allows an authenticated MCP client to read and delete arbitrary files through a path traversal vulnerability in the database_clean MCP tool. Users of affected versions should take immediate action to mitigate the vulnerability. This debrief provides an overview of the vulnerability, its impact, and recommended actions for affected parties.

Vendor
SiYuan
Product
SiYuan kernel
CVSS
CRITICAL 9.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-17
Original CVE updated
2026-08-26
Advisory published
2026-08-17
Advisory updated
2026-08-26

Who should care

Users of SiYuan kernel versions before v3.7.4, administrators of systems using SiYuan, security teams monitoring for potential path traversal vulnerabilities, and operators responsible for maintaining and securing SiYuan deployments should be aware of this vulnerability and take necessary actions to mitigate it.

Technical summary

The database_clean MCP tool in SiYuan kernel before v3.7.4 performs an empty-string check on the id parameter before passing it to RemoveUnusedAttributeView, which builds a filesystem path via filepath.Join without validating that id matches SiYuan's node-ID format. This allows an authenticated MCP client to supply path traversal sequences in id to cause the kernel to copy an arbitrary file readable by the process into SiYuan's history directory and then delete the original file. The vulnerability has been reported and verified through limited evidence.

Defensive priority

Authenticated clients can exploit this vulnerability to read and delete arbitrary files.

Recommended defensive actions

  • Inventory and verify SiYuan kernel versions, ensuring v3.7.4 or later is deployed.
  • Restrict access to MCP clients to trusted sources only.
  • Monitor for unusual file read and deletion activities in SiYuan's history directory.
  • Implement compensating controls such as file access controls and monitoring.
  • Exception tracking for file operations in SiYuan's history directory.

Evidence notes

The vulnerability exists in SiYuan kernel before v3.7.4 in the database_clean MCP tool, allowing for path traversal. An authenticated MCP client can supply path traversal sequences to cause the kernel to copy an arbitrary file readable by the process into SiYuan's history directory and then delete the original file. The vulnerability was reported via a source reference and has been verified through limited evidence.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-74798 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-74798

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-74798 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-74798

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.