Summary
SiYuan: Authorization Bypass Allows Low-Privilege Publish User to Modify Notebook Content via /api/block/appendHeadingChildren
Impact
This vulnerability allows any authenticated publish user with read-only privileges (RoleReader) to modify notebook content.
Potential impacts include:
• Unauthorized modification of private notes
• Content tampering in published notebooks
• Loss of data integrity
• Possible chaining with other API endpoints to escalate further privileges
The issue occurs because write operations are protected only by CheckAuth rather than enforcing role-based authorization checks.
The application does not perform an authorization check before performing a sensitive operation. Typical impact: unauthorized access to restricted functionality or data.
CVE-2026-30926 has a CVSS score of 7.1 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
In the interim: Keep the dependency up to date. Ensure authorization checks are enforced consistently on all sensitive operations.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-30926? CVE-2026-30926 is a high-severity missing authorization vulnerability in github.com/siyuan-note/siyuan/kernel (go), affecting versions <= 0.0.0-20260304035530-d03ebdec8279. No fixed version is listed yet. The application does not perform an authorization check before performing a sensitive operation.
- How severe is CVE-2026-30926? CVE-2026-30926 has a CVSS score of 7.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/siyuan-note/siyuan/kernel are affected by CVE-2026-30926? github.com/siyuan-note/siyuan/kernel (go) versions <= 0.0.0-20260304035530-d03ebdec8279 is affected.
- Is there a fix for CVE-2026-30926? No fixed version is listed for CVE-2026-30926 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2026-30926 exploitable, and should I be worried? Whether CVE-2026-30926 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-30926 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-30926? No fixed version is listed yet. In the interim: Keep the dependency up to date. Ensure authorization checks are enforced consistently on all sensitive operations.