# CVE-2026-85579: SiYuan before v3.8.2 Information Disclosure via undoState

> An authenticated reader can leak internal root IDs of private documents via the undoState API, exposing cross-document relationships.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-6gf8-q9ch-w732, GHSA-pf8f-99x6-h9q4

## What is CVE-2026-85579?

CVE-2026-85579 is a medium-severity vulnerability in siyuan-note siyuan, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

SiYuan is affected by an information disclosure vulnerability (confirmed in v3.8.1, fixed in v3.8.2) in the reader-accessible POST /api/transactions/undoState endpoint. The endpoint returns the peekMutatedRootIDs list from the global undo-log stack for a caller-supplied root ID without applying publish-access visibility filtering. An authenticated reader who knows the root ID of a visible document can obtain the internal root IDs of other documents (including private or unpublished ones) modified in the same cross-document transaction, disclosing internal identifiers and cross-document relationships. Document body contents are not directly exposed.

Weakness: CWE-639 (Authorization Bypass Through User-Controlled Key)

## Which versions are affected by CVE-2026-85579?


## How do I fix CVE-2026-85579?

No fix has been published for CVE-2026-85579 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-85579 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85579 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85579 and fix it if it is affected.

What it is: CVE-2026-85579 is a medium-severity vulnerability in siyuan-note siyuan, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85579 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-2026-85579/ (Markdown: https://insights.sbomify.com/CVE-2026-85579/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85579
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85579
- OSV: https://osv.dev/vulnerability/CVE-2026-85579

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85579/
Summaries are generated and may contain mistakes; the official description above is the record.