# CVE-2026-66396: SiYuan before v3.7.2 Stored XSS to RCE via title-img IAL

> Attackers with editor permissions can inject scripts into document titles to execute arbitrary code via Node.js when victims view the document.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 27 Jul 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-5rxg-wh59-mg34, GHSA-pwp5-qq97-mcqc

## What is CVE-2026-66396?

CVE-2026-66396 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 27 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

SiYuan before v3.7.2 fails to escape the title-img Individual Attribute List value when rendering Gallery and Kanban cover images, allowing stored cross-site scripting via unescaped style attribute interpolation. Attackers with editor permissions can inject onload handlers that execute arbitrary code in the Electron renderer with full Node.js access when victims open affected documents.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-66396?


## How do I fix CVE-2026-66396?

No fix has been published for CVE-2026-66396 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-66396 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66396 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-66396 and fix it if it is affected.

What it is: CVE-2026-66396 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 27 Jul 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-66396 exists.

Affected product: siyuan-note siyuan. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-66396/ (Markdown: https://insights.sbomify.com/CVE-2026-66396/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-66396
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-66396
- OSV: https://osv.dev/vulnerability/CVE-2026-66396

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-66396/
Summaries are generated and may contain mistakes; the official description above is the record.