GHSA-FF66-236V-P4FG
Vulnerability from github – Published: 2026-04-01 00:05 – Updated: 2026-04-01 00:05Summary
A vulnerability allows crafted block attribute values to bypass server-side attribute escaping when an HTML entity is mixed with raw special characters. An attacker can embed a malicious IAL value inside a .sy document, package it as a .sy.zip, and have the victim import it through the normal Import -> SiYuan .sy.zip workflow. Once the note is opened, the malicious attribute breaks out of its original HTML context and injects an event handler, resulting in stored XSS. In the Electron desktop client, this XSS reaches remote code execution because injected JavaScript runs with access to Node/Electron APIs.
Details
The issue is caused by a logic regression in escapeNodeAttributeValues in kernel/filesys/tree.go.
Previously, the escaping logic converted node.KramdownIAL with parse.IAL2Map(...) before deciding whether a value needed escaping. That conversion unescaped existing entities first, so mixed values such as:
&" onmouseenter="alert('IAL-XSS')
were still recognized as unsafe and escaped correctly.
The logic changed to inspect raw KramdownIAL values directly. The new needsEscapeForValue implementation returns false as soon as it sees any known entity such as &, ", <, or >. This means a value containing both an entity and an unescaped raw quote bypasses escaping entirely.
That bypass becomes exploitable because the renderer later inserts block IAL values directly into HTML attributes. A payload like:
&" onmouseenter="require('child_process').exec('calc')
can be rendered into HTML equivalent to:
<div title="&" onmouseenter="require('child_process').exec('calc')">
This creates a stored XSS condition. In SiYuan Desktop, the Electron renderer runs with Node.js integration available, so attacker-controlled JavaScript can invoke Node APIs directly. As a result, the issue is not limited to script execution in the page context and becomes arbitrary command execution on the victim’s machine.
The stored XSS path was validated by importing a crafted .sy.zip through the normal GUI and triggering JavaScript execution from the rendered block. Because the same injected JavaScript runs in the privileged Electron renderer, this is an RCE issue in the desktop client.
PoC
- Start SiYuan Desktop
v3.6.1. - Prepare a crafted
.sy.zipcontaining a .sy document with a block IAL property such as:
"title": "&\" onmouseenter=\"require('child_process').exec('calc')"
- In the UI, right-click any notebook.
- Select
Import -> SiYuan .sy.zip. - Import the crafted archive.
- Open the imported note.
- Move the mouse over the affected paragraph block.
- Observe that the injected JavaScript executes.
- On Windows,
calc.exelaunches, demonstrating arbitrary command execution.
Impact
This vulnerability allows an attacker to deliver a malicious .sy.zip file that executes attacker-controlled JavaScript after import. In the desktop application, that JavaScript runs with Node/Electron privileges and can execute arbitrary operating system commands under the victim’s account. This makes the bug equivalent to local code execution triggered by importing and opening attacker-supplied content.
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/siyuan-note/siyuan/kernel"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.0.0-20260329142331-918d1bd9f967"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-34585"
],
"database_specific": {
"cwe_ids": [
"CWE-79",
"CWE-94"
],
"github_reviewed": true,
"github_reviewed_at": "2026-04-01T00:05:11Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\nA vulnerability allows crafted block attribute values to bypass server-side attribute escaping when an HTML entity is mixed with raw special characters. An attacker can embed a malicious IAL value inside a `.sy` document, package it as a `.sy.zip`, and have the victim import it through the normal `Import -\u003e SiYuan .sy.zip` workflow. Once the note is opened, the malicious attribute breaks out of its original HTML context and injects an event handler, resulting in stored XSS. In the Electron desktop client, this XSS reaches remote code execution because injected JavaScript runs with access to Node/Electron APIs.\n\n### Details\nThe issue is caused by a logic regression in `escapeNodeAttributeValues` in `kernel/filesys/tree.go`.\nPreviously, the escaping logic converted `node.KramdownIAL` with `parse.IAL2Map(...)` before deciding whether a value needed escaping. That conversion unescaped existing entities first, so mixed values such as:\n```\n\u0026amp;\" onmouseenter=\"alert(\u0027IAL-XSS\u0027)\n```\nwere still recognized as unsafe and escaped correctly.\nThe logic changed to inspect raw `KramdownIAL` values directly. The new `needsEscapeForValue` implementation returns `false` as soon as it sees any known entity such as `\u0026amp;`, `\u0026quot;`, `\u0026lt;`, or `\u0026gt;`. This means a value containing both an entity and an unescaped raw quote bypasses escaping entirely.\n\nThat bypass becomes exploitable because the renderer later inserts block IAL values directly into HTML attributes. A payload like:\n```\n\u0026amp;\" onmouseenter=\"require(\u0027child_process\u0027).exec(\u0027calc\u0027)\n```\ncan be rendered into HTML equivalent to:\n```\n\u003cdiv title=\"\u0026amp;\" onmouseenter=\"require(\u0027child_process\u0027).exec(\u0027calc\u0027)\"\u003e\n```\nThis creates a stored XSS condition. In SiYuan Desktop, the Electron renderer runs with Node.js integration available, so attacker-controlled JavaScript can invoke Node APIs directly. As a result, the issue is not limited to script execution in the page context and becomes arbitrary command execution on the victim\u2019s machine.\n\nThe stored XSS path was validated by importing a crafted `.sy.zip` through the normal GUI and triggering JavaScript execution from the rendered block. Because the same injected JavaScript runs in the privileged Electron renderer, this is an RCE issue in the desktop client.\n\n### PoC\n1. Start SiYuan Desktop `v3.6.1`.\n2. Prepare a crafted `.sy.zip` containing a .sy document with a block IAL property such as:\n```\n\"title\": \"\u0026amp;\\\" onmouseenter=\\\"require(\u0027child_process\u0027).exec(\u0027calc\u0027)\"\n```\n3. In the UI, right-click any notebook.\n4. Select `Import -\u003e SiYuan .sy.zip`.\n5. Import the crafted archive.\n6. Open the imported note.\n7. Move the mouse over the affected paragraph block.\n8. Observe that the injected JavaScript executes.\n9. On Windows, `calc.exe` launches, demonstrating arbitrary command execution.\n\n### Impact\nThis vulnerability allows an attacker to deliver a malicious `.sy.zip` file that executes attacker-controlled JavaScript after import. In the desktop application, that JavaScript runs with Node/Electron privileges and can execute arbitrary operating system commands under the victim\u2019s account. This makes the bug equivalent to local code execution triggered by importing and opening attacker-supplied content.",
"id": "GHSA-ff66-236v-p4fg",
"modified": "2026-04-01T00:05:11Z",
"published": "2026-04-01T00:05:11Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-ff66-236v-p4fg"
},
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/commit/918d1bd9f967d888f474f6764744a3d8cca4a501"
},
{
"type": "PACKAGE",
"url": "https://github.com/siyuan-note/siyuan"
},
{
"type": "WEB",
"url": "https://github.com/siyuan-note/siyuan/releases/tag/v3.6.2"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "SiYuan Desktop: Stored XSS in imported .sy.zip content leads to arbitrary command execution"
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.