Reader-level note modification via unchecked block append
Published Mar 9, 2026 · Updated Mar 9, 2026
Missing authorization in SiYuan before 3.5.10 allows remote authenticated users to append blocks through its publish service. The /api/block/appendHeadingChildren route applies CheckAuth, which admits RoleReader sessions, but omits CheckAdminRole and CheckReadonly before persisting childrenDOM. A read-only publish account and an existing heading identifier are required; successful requests write attacker-controlled blocks into stored notes without granting broader administrative access.
Summary
What happened
Missing authorization in SiYuan before 3.5.10 allows remote authenticated users to append blocks through its publish service. The /api/block/appendHeadingChildren route applies CheckAuth, which admits RoleReader sessions, but omits CheckAdminRole and CheckReadonly before persisting childrenDOM. A read-only publish account and an existing heading identifier are required; successful requests write attacker-controlled blocks into stored notes without granting broader administrative access.
The record
- CVE
- CVE-2026-30926
- Published
- Mar 9, 2026
- Updated
- Mar 9, 2026
- Vendor
- SiYuan Note
- Product
- SiYuan
- Classifications
- CWE-862, CWE-284, T1565.001
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 9, 2026CVE publishedPublication date reported by the CVE source.
- Mar 9, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.5.10
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-f9cq-v43p-v523 RoleReader write proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo