# CVE-2026-72812: SiYuan before v3.7.4 Missing Authorization via refreshBacklink

> Attackers can trigger persistent server-side writes and resource amplification via an unauthenticated API endpoint, bypassing read-only protections.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/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:** 14 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-wgwx-479j-23vq, GO-2026-6408

## What is CVE-2026-72812?

CVE-2026-72812 is a medium-severity missing authorization vulnerability in siyuan-note siyuan, published on 14 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

SiYuan versions before v3.7.4 contain a missing authorization vulnerability in the /api/ref/refreshBacklink endpoint that allows anonymous readers to trigger persistent server-side writes. Attackers can invoke the endpoint with an attacker-controlled block ID to flush transaction queues, scan all references globally, and enqueue database writes, bypassing read-only protections and enabling resource amplification attacks.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-72812?

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 | 0.0.0-20260723002528-7d273c271ce1 |
| `github.com/siyuan-note/siyuan/kernel` | Go | All versions | 0.0.0-20260723002528-7d273c271ce1 |
| `github.com/siyuan-note/siyuan/kernel` | Go | All versions | 0.0.0-20260723002528-7d273c271ce1 |

## How do I fix CVE-2026-72812?

Upgrade github.com/siyuan-note/siyuan/kernel to 0.0.0-20260723002528-7d273c271ce1 or later.

## Is CVE-2026-72812 being exploited?

There is no known exploitation of CVE-2026-72812 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72812 and fix it if it is affected.

What it is: CVE-2026-72812 is a medium-severity missing authorization vulnerability in siyuan-note siyuan, published on 14 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-72812 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260723002528-7d273c271ce1
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260723002528-7d273c271ce1
- github.com/siyuan-note/siyuan/kernel (Go): affected all versions; fixed in 0.0.0-20260723002528-7d273c271ce1

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-2026-72812/ (Markdown: https://insights.sbomify.com/CVE-2026-72812/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72812
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72812
- OSV: https://osv.dev/vulnerability/CVE-2026-72812

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72812/
Summaries are generated and may contain mistakes; the official description above is the record.