Remote Code Execution in SiYuan via permissive CORS and API JavaScript injection
CVE-2026-34449 affects SiYuan desktop versions prior to 3.6.2. The vulnerability is caused by an overly permissive cross-origin configuration that exposes the local application API to arbitrary websites by returning Access-Control-Allow-Origin: * together with Access-Control-Allow-Private-Network: true. A malicious website visited while SiYuan is running can send cross-origin requests to the local SiYuan API and inject a JavaScript snippet. That injected code is later executed when the user opens the SiYuan UI, and because the UI runs in Electron with Node.js context available, the attacker-controlled JavaScript executes with full operating system access. This results in remote code execution on the host running SiYuan.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.