# CVE-2026-74904: SiYuan before v3.7.4 Missing Authorization via block API

> Attackers can read private block content and metadata in SiYuan when publish mode is enabled due to missing authorization checks.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-4vpg-gwqq-w44c, GO-2026-6654

## What is CVE-2026-74904?

CVE-2026-74904 is a high-severity missing authorization vulnerability in siyuan-note siyuan, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SiYuan before v3.7.4 is missing authorization checks in 17 block metadata/content endpoints in kernel/api/block.go (including getRefText, checkBlockExist, and getBlockBreadcrumb). These handlers are gated only by basic authentication (model.CheckAuth) and lack publish-access filtering, allowing anonymous publish-mode readers to disclose private block content-derived text, structural metadata, and existence information for arbitrary block IDs across the workspace.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-74904?

3 open source packages ship an affected version, including github.com/siyuan-note/siyuan/kernel.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/siyuan-note/siyuan/kernel` | Go | All versions | 0.0.0-20260804015139-bd067a4fe9b2 |
| `github.com/siyuan-note/siyuan/kernel` | Go | All versions | 0.0.0-20260804015139-bd067a4fe9b2 |
| `github.com/siyuan-note/siyuan/kernel` | Go | All versions | 0.0.0-20260804015139-bd067a4fe9b2 |

## How do I fix CVE-2026-74904?

Upgrade github.com/siyuan-note/siyuan/kernel to 0.0.0-20260804015139-bd067a4fe9b2 or later.

## Is CVE-2026-74904 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74904 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74904 and fix it if it is affected.

What it is: CVE-2026-74904 is a high-severity missing authorization vulnerability in siyuan-note siyuan, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-74904 exists.

Affected packages and fixed versions:
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260804015139-bd067a4fe9b2
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260804015139-bd067a4fe9b2
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260804015139-bd067a4fe9b2

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-2026-74904/ (Markdown: https://insights.sbomify.com/CVE-2026-74904/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74904
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74904
- OSV: https://osv.dev/vulnerability/CVE-2026-74904

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74904/
Summaries are generated and may contain mistakes; the official description above is the record.