CVE-2026-72790: SiYuan Information Disclosure Vulnerability

CVE-2026-72790 Overview

CVE-2026-72790 is an information disclosure vulnerability in SiYuan, an open-source personal knowledge management application. Versions before v3.7.4 expose notebook metadata through the /api/notebook/getNotebookInfo endpoint without enforcing authorization checks. Unauthenticated attackers can retrieve notebook names, document counts, storage sizes, and timestamps for closed or non-published notebooks that should remain hidden from readers. The issue is classified under CWE-862: Missing Authorization and affects deployments where SiYuan is reachable over the network.

Critical Impact
Remote unauthenticated attackers can enumerate metadata for private SiYuan notebooks, revealing existence, size, and activity patterns of content intended to be hidden.

Affected Products

SiYuan versions prior to v3.7.4
Self-hosted SiYuan instances exposed to untrusted networks
Shared or multi-user SiYuan deployments serving reader accounts

Discovery Timeline

2026-08-12 - CVE-2026-72790 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-72790

Vulnerability Analysis

The vulnerability resides in SiYuan's notebook information API. The /api/notebook/getNotebookInfo endpoint returns metadata about any notebook by identifier without validating that the requester has permission to view it. SiYuan supports concepts of closed notebooks and non-published notebooks that reader-role users should not see. The affected endpoint bypasses these visibility controls entirely.

An attacker who can reach the SiYuan HTTP interface can query the endpoint for notebook identifiers and receive structured responses describing the notebook name, document count, on-disk size, and creation or modification timestamps. While the endpoint does not return note contents, the exposed metadata still constitutes a confidentiality breach for users who rely on notebook visibility settings to segment private material.

Root Cause

The root cause is a missing authorization check on the getNotebookInfo handler. The endpoint reads notebook state from the server and serializes it back to the caller without evaluating the caller's role or the notebook's published state. This is a classic CWE-862 pattern where an access control decision is absent from a sensitive read path.

Attack Vector

Exploitation requires only network access to the SiYuan service. No credentials, user interaction, or elevated privileges are needed. An attacker enumerates or guesses notebook identifiers and issues HTTP requests directly to the vulnerable endpoint. Responses reveal metadata for closed and non-published notebooks that the SiYuan UI would otherwise hide from readers.

See the GitHub Security Advisory GHSA-74pj-6g7r-j55c and the VulnCheck Advisory for additional technical detail.

Detection Methods for CVE-2026-72790

Indicators of Compromise

Unexpected HTTP requests to /api/notebook/getNotebookInfo from unfamiliar source IP addresses.
Bursts of sequential or high-volume calls to the notebook API suggesting identifier enumeration.
Access log entries showing getNotebookInfo requests without preceding authenticated session activity.

Detection Strategies

Review SiYuan HTTP access logs for requests to /api/notebook/getNotebookInfo originating from outside expected user sessions.
Correlate API calls against the notebook visibility state to identify reads targeting closed or non-published notebooks.
Deploy web application firewall rules that flag high-frequency access to notebook metadata endpoints.

Monitoring Recommendations

Forward SiYuan reverse-proxy and application logs to a centralized logging platform for retention and query.
Alert on unauthenticated or anonymous requests reaching notebook API paths that should require a session.
Track baseline request rates for /api/notebook/* and generate alerts when traffic deviates significantly.

How to Mitigate CVE-2026-72790

Immediate Actions Required

Upgrade SiYuan to version v3.7.4 or later, which introduces authorization checks on the affected endpoint.
Restrict network exposure of SiYuan instances to trusted users and networks until patching is complete.
Audit reader accounts and shared instances to identify potential prior enumeration activity.

Patch Information

The SiYuan maintainers addressed the issue in v3.7.4. Refer to the GitHub Security Advisory GHSA-74pj-6g7r-j55c for the official patch reference and release notes.

Workarounds

Place SiYuan behind an authenticating reverse proxy that enforces access control before requests reach the application.
Block external access to /api/notebook/getNotebookInfo at the reverse proxy or web application firewall until the upgrade is applied.
Bind SiYuan to a loopback or private interface and access it through a VPN when public exposure is not required.

bash

# Example nginx snippet to block unauthenticated access to the vulnerable endpoint
location = /api/notebook/getNotebookInfo {
    deny all;
    return 403;
}