Vulnerability · Published Sep 26, 2026 · Assigned by VulnCheck

CVE-2026-100641SiYuan before v3.8.4 Stored XSS via Unescaped Flashcard Content

High 8.0

In plain English

A high-severity cross-site scripting in siyuan from siyuan-note. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 52% of all known vulnerabilities).

Severity (CVSS 3.1)8.0High

Exploit odds (30 days)0.7%top 47.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

SiYuan before v3.8.4 does not HTML-escape stored flashcard block content before interpolating it into the card-manager list markup. Block content returned by /api/riff/getRiffCards is inserted into a card item template in app/src/card/viewCards.ts and assigned to listElement.innerHTML, so content such as <img src=invalid onerror=...> becomes an executable event-handler attribute. Because the SiYuan desktop (Electron) main window is created with nodeIntegration enabled and contextIsolation disabled, an administrator who opens the card manager on a workspace containing attacker-supplied flashcard content (for example introduced through contribution or import) executes the attacker's script in a privileged renderer, which can lead to arbitrary code execution on the host. The affected endpoint remains behind authentication and administrator-role checks; this is an untrusted-content-to-privileged-renderer issue, not an authorization bypass.

Affected products (as reported)

Vendor	Product	Versions
siyuan-note	siyuan	0 – before 3.8.4

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-2mmf-4xwm-55rm) vendor-advisory
Patch Commit patch
Patch Commit patch
Patch Commit patch
Patch Commit patch
VulnCheck Advisory: SiYuan before v3.8.4 Stored XSS via Unescaped Flashcard Content third-party-advisory