CVE-2026-72790 in SiYuan
Summary
by MITRE • 08/12/2026
SiYuan before v3.7.4 contains an information disclosure vulnerability in the /api/notebook/getNotebookInfo endpoint that returns notebook metadata without authorization checks. Attackers can read notebook names, document counts, sizes, and timestamps for closed or non-published notebooks that should be hidden from readers.
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Analysis
by VulDB Data Team • 08/12/2026
The SiYuan note-taking application prior to version 3.7.4 suffers from a critical information disclosure vulnerability within its /api/notebook/getNotebookInfo endpoint that fundamentally undermines the application's access control mechanisms. This vulnerability represents a direct violation of the principle of least privilege and demonstrates a severe failure in authorization implementation that allows unauthenticated or unauthorized users to access sensitive metadata about notebooks that should remain private. The flaw exists at the API level where proper authentication and authorization checks are absent, enabling attackers to retrieve comprehensive information about notebook structures without any form of verification.
The technical nature of this vulnerability aligns with CWE-200, which specifically addresses improper exposure of sensitive information, and falls under the broader category of insufficient authorization flaws. When an attacker makes a request to the /api/notebook/getNotebookInfo endpoint, the system returns detailed metadata including notebook names, document counts, storage sizes, and timestamp information for notebooks that are either closed or not published. This exposure extends beyond simple data leakage as it provides attackers with structural intelligence about the application's content organization, potentially enabling more sophisticated attacks such as targeted enumeration of sensitive documents or identification of high-value targets within the system.
The operational impact of this vulnerability is significant and multifaceted, creating opportunities for attackers to conduct reconnaissance activities that could lead to further exploitation. By accessing notebook metadata, adversaries gain insights into document hierarchies, content volume distributions, and temporal patterns of note creation, which can inform subsequent attacks targeting specific notebook contents or users. This information disclosure vulnerability directly conflicts with the ATT&CK technique T1213.002 for Data from Information Repositories, as it provides unauthorized access to repository metadata that would normally be protected within a secure application environment.
The vulnerability affects all notebook types regardless of their publication status or access restrictions, meaning that even closed notebooks containing sensitive information remain vulnerable to metadata extraction. This represents a fundamental flaw in the application's security architecture where the distinction between public and private content is not properly enforced at the API level. The lack of authorization checks during metadata retrieval operations creates an attack surface that could be leveraged by threat actors to build detailed profiles of user content patterns, potentially enabling social engineering attacks or targeted data exfiltration attempts.
Organizations using SiYuan versions prior to 3.7.4 should immediately implement mitigations including mandatory authentication for all API endpoints, enforcement of access controls based on user permissions and notebook ownership, and implementation of proper authorization verification mechanisms. The recommended remediation involves patching to version 3.7.4 or later where the authorization checks have been properly implemented to ensure that only authorized users can access notebook metadata. Additionally, network-level protections such as API rate limiting and monitoring for unusual access patterns should be implemented to detect potential exploitation attempts. Security teams should also conduct thorough audits of all API endpoints to identify similar authorization gaps and implement comprehensive logging of metadata access events to support incident response activities.