# CVE-2026-23852: SiYuan vulnerable to Stored XSS / RCE via `setBlockAttrs` icon attribute

> Attackers can inject malicious HTML into block icons via API, causing stored XSS and potential remote code execution in the desktop application.

- **Severity:** Medium 5.8 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 19 Jan 2026
- **Updated:** 20 Jan 2026
- **Also known as:** GHSA-7c6g-g2hx-23vv

## What is CVE-2026-23852?

CVE-2026-23852 is a medium-severity cross-site scripting vulnerability in B3log Siyuan, published on 19 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

SiYuan is a personal knowledge management system. Versions prior to 3.5.4 have a stored Cross-Site Scripting (XSS) vulnerability that allows an attacker to inject arbitrary HTML attributes into the `icon` attribute of a block via the `/api/attr/setBlockAttrs` API. The payload is later rendered in the dynamic icon feature in an unsanitized context, leading to stored XSS and, in the desktop environment, potential remote code execution (RCE). This issue bypasses the previous fix for issue `#15970` (XSS → RCE via dynamic icons). Version 3.5.4 contains an updated fix.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-94 (Improper Control of Generation of Code)

## Which versions are affected by CVE-2026-23852?

It affects 1 product.


Products: B3log Siyuan.

## How do I fix CVE-2026-23852?

No fix has been published for CVE-2026-23852 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-23852 being exploited?

There is no known exploitation of CVE-2026-23852 in the wild and no public exploit code.

## Other vulnerabilities in B3log Siyuan

- [CVE-2026-32938](https://insights.sbomify.com/CVE-2026-32938/): SiYuan has an Arbitrary File Read in its Desktop Publish Service (critical 9.9)
- [CVE-2026-33669](https://insights.sbomify.com/CVE-2026-33669/): SiYuan has Arbitrary Document Reading within the Publishing Service (critical 9.8)
- [CVE-2026-33670](https://insights.sbomify.com/CVE-2026-33670/): SiYuan has directory traversal within its publishing service (critical 9.8)
- [CVE-2026-32767](https://insights.sbomify.com/CVE-2026-32767/): SiYuan: Authorization Bypass Allows Arbitrary SQL Execution via Search API (critical 9.8)
- [CVE-2024-53504](https://insights.sbomify.com/CVE-2024-53504/): SQL injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23852 and fix it if it is affected.

What it is: CVE-2026-23852 is a medium-severity cross-site scripting vulnerability in B3log Siyuan, published on 19 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-23852 in the wild and no public exploit code.

Affected product: B3log 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-2026-23852/ (Markdown: https://insights.sbomify.com/CVE-2026-23852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23852
- OSV: https://osv.dev/vulnerability/CVE-2026-23852

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23852/
Summaries are generated and may contain mistakes; the official description above is the record.