---
id: CVE-2026-74902
title: >-
  SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file
  upload validation flow that fails to escape filenames before inserting them
  into HTML via insertAdjacentHTML
summary: >-
  SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file
  upload validation flow that fails to escape filenames before inserting them
  into HTML via insertAdjacentHTML. Attackers can craft a malicious filename
  contain…
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'
cwe:
  - CWE-79
vendor: siyuan-note
product: siyuan
affected:
  - siyuan < 3.7.4
published: '2026-08-18'
updated: '2026-10-08'
sourceUpdated: '2026-10-08T16:17:40.330'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74902'
references:
  - url: >-
      https://github.com/siyuan-note/siyuan/security/advisories/GHSA-jf56-jrhq-j2qp
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/siyuan-before-xss-to-rce-via-malicious-filename-upload
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-08-18T12:52:00.846926Z'
epss: 0.00198
epssPercentile: 0.08786
ingestedAt: '2026-10-08T16:52:14.721Z'
---

## Overview

SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML. Attackers can craft a malicious filename containing script payloads that execute with full OS command access when a user drags, drops, or pastes the file into the editor.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.