8.8High
CVE-2026-86712
SiYuan before 3.8.2 trusts the attacker-writable text/siyuan clipboard MIME type and skips sanitization in the paste handler, allowing code execution in the Node-enabled desktop renderer. Attackers can craft malicious web pages that write to the clipboard, and when pasted into SiYuan, injected scripts execute with full Node.js access through the Electron main process.
What this means for your business
- An attacker can use it remotely, over a network, without a login, but only after tricking someone into an action such as opening a file or a link.
- FIRST's prediction model gives it a 0.4% chance of attack attempts being seen in the next 30 days, ranking above 31% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 8.8 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H- CVSS v4
- 8.6
- Weakness
- CWE-79
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-09-08
- Last modified
- 2026-09-10
- Sources
- NVD
References
- https://github.com/siyuan-note/siyuan
- https://github.com/siyuan-note/siyuan/blob/v3.8.1/app/src/protyle/util/paste.ts
- https://github.com/siyuan-note/siyuan/commit/9ce660652de2ced26ec2d98a5a242cb0b8bb7273
- https://github.com/siyuan-note/siyuan/releases/tag/v3.8.2
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-9rr9-pxr4-gcgc
- https://www.vulncheck.com/advisories/siyuan-before-3.8.2-remote-code-execution-via-clipboard