SiYuan: Authorization Bypass Allows Low-Privilege Publish User to Modify Notebook Content via /api/block/appendHeadingChildren

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.1 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

EPSS

• CVE-2026-30926: 0.32% estimated exploitation activity in the next 30 days; percentile 25.45 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A privilege escalation vulnerability exists in the publish service of SiYuan Note that allows a low-privilege publish account (RoleReader) to modify notebook content via the /api/block/appendHeadingChildren API endpoint. The endpoint only requires model.CheckAuth, which accepts RoleReader sessions. Because the endpoint performs a persistent document mutation and does not enforce CheckAdminRole or CheckReadonly, a publish user with read-only privileges can append new blocks to existing documents. This allows remote authenticated publish users to modify notebook content and compromise the integrity of stored notes. Details File: router.go, block.go, block.go, session.go Lines: router.go:245, api/block.go:193-205, model/block.go:688-714, model/session.go:201-209 Vulnerable Code: Why Vulnerable: A low-privilege publish account (RoleReader, read-only) passes CheckAuth, but this write endpoint lacks CheckAdminRole and CheckReadonly. The handler performs persistent document writes.…

Published by the source

9 Mar 2026, 18:18 UTC

Last modified by the source

10 Mar 2026, 18:39 UTC

Source last checked

26 Oct 2026, 15:15 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f9cq-v43p-v523

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# Patch Next advisory brief: CVE-2026-30926

Advisory: SiYuan: Authorization Bypass Allows Low-Privilege Publish User to Modify Notebook Content via /api/block/appendHeadingChildren
IDs: CVE-2026-30926, GHSA-f9cq-v43p-v523
Record: https://patchnext.com/advisories/cve-2026-30926 (revision 1, source checked 26 Oct 2026, 15:15 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/siyuan-note/siyuan/kernel: affected <= 0.0.0-20260304035530-d03ebdec8279

## Suggested inspection (read-only)
- Go github.com/siyuan-note/siyuan/kernel: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/siyuan-note/siyuan/kernel.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f9cq-v43p-v523 (GitHub-reviewed advisory GHSA-f9cq-v43p-v523 lists affected ranges: Go github.com/siyuan-note/siyuan/kernel >=0 <=0.0.0-20260304035530-d03ebdec8279)

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