# CVE-2026-75916: SiYuan XSS-to-RCE via unescaped block metadata in hint popup

> Attackers can execute arbitrary OS commands by injecting scripts into block metadata, exploiting XSS in the autocomplete popup of the SiYuan desktop application.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 19 Aug 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-5prr-vgxq-69g9, GHSA-962c-hgx6-ffmx

## What is CVE-2026-75916?

CVE-2026-75916 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 19 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

SiYuan through 3.7.3 contains a cross-site scripting vulnerability in the '((' block-reference autocomplete hint popup. In genHintItemHTML() (app/src/protyle/hint/extend.ts), a candidate block's name, alias, and memo fields are concatenated into the popup's HTML without escaping. An attacker who can set these metadata fields on a block can inject a self-firing payload (e.g. <img src=x onerror=...>) that executes automatically when a victim types '((' followed by a search term that surfaces the crafted block. Because SiYuan's Electron windows run with nodeIntegration enabled, contextIsolation disabled, and no CSP, the injected script gains require('child_process') access, allowing the XSS to escalate to arbitrary OS command execution.

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

## Which versions are affected by CVE-2026-75916?


## How do I fix CVE-2026-75916?

No fix has been published for CVE-2026-75916 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-75916 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-75916 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-75916 and fix it if it is affected.

What it is: CVE-2026-75916 is a critical cross-site scripting vulnerability in siyuan-note siyuan, published on 19 Aug 2026. It can only be exploited from the same machine or local network, 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-2026-75916 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-2026-75916/ (Markdown: https://insights.sbomify.com/CVE-2026-75916/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-75916
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-75916
- OSV: https://osv.dev/vulnerability/CVE-2026-75916

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-75916/
Summaries are generated and may contain mistakes; the official description above is the record.