CVE-2026-72795 Overview
CVE-2026-72795 is a critical authorization flaw in SiYuan, an open-source personal knowledge management application. Versions before v3.7.4 fail to enforce publish access controls on embedded block content. The getBlockDOMWithEmbed and getBlockDOMsWithEmbed endpoints return content from documents regardless of their protection status. Unauthenticated attackers can request published blocks containing embed queries to read content from password-protected, hidden, or forbidden documents. The vulnerability is classified as [CWE-862] Missing Authorization and is exploitable remotely over the network without user interaction.
Critical Impact
Unauthenticated remote attackers can extract confidential content from password-protected, hidden, or restricted SiYuan documents by abusing embed-block API endpoints.
Affected Products
- SiYuan versions prior to v3.7.4
- SiYuan getBlockDOMWithEmbed endpoint
- SiYuan getBlockDOMsWithEmbed endpoint
Discovery Timeline
- 2026-08-12 - CVE-2026-72795 published to NVD
- 2026-08-12 - Last updated in NVD database
Technical Details for CVE-2026-72795
Vulnerability Analysis
SiYuan supports embed blocks that dynamically pull content from other documents using queries. The two affected endpoints, getBlockDOMWithEmbed and getBlockDOMsWithEmbed, render embedded block content when a published block containing an embed query is requested. The server resolves the embed query and returns the results without checking whether the caller has permission to view the source documents. This missing authorization check allows attackers to pivot from any publicly accessible published block into content that the site owner explicitly restricted.
Because embed queries can target arbitrary documents in the workspace, an attacker who identifies or crafts a suitable embed can enumerate and exfiltrate protected notes. The scope change reflected in the CVSS vector captures this pivot: a request to a public resource returns data from a distinct, restricted resource.
Root Cause
The root cause is a missing access-control check in the block-rendering path. The endpoints trust the embed query to define which content should be returned, without re-validating that the requester holds publish access to each embedded document. Password protection, hidden flags, and forbidden-document markers are enforced elsewhere in the application but bypassed on this code path.
Attack Vector
Attackers send unauthenticated HTTP requests to a SiYuan instance that exposes published content. The request targets a block that contains, or can be induced to contain, an embed query referencing protected documents. The server returns the rendered Document Object Model (DOM) including the restricted block content. Refer to the GitHub Security Advisory GHSA-h6w7-xxcf-w2mq and the VulnCheck Advisory on Siyuan for further technical detail.
Detection Methods for CVE-2026-72795
Indicators of Compromise
- Unauthenticated HTTP requests to /api/block/getBlockDOMWithEmbed or /api/block/getBlockDOMsWithEmbed from unfamiliar source addresses.
- Repeated requests enumerating block identifiers, particularly from a single client in a short window.
- Access-log entries showing successful 200 responses for embed endpoints where the referenced document is marked password-protected or hidden.
Detection Strategies
- Baseline normal traffic to SiYuan embed endpoints and alert on volume spikes or access from external IP ranges.
- Correlate embed-endpoint requests with document metadata to flag responses that include content from restricted documents.
- Inspect web application firewall (WAF) logs for anomalous query parameters targeting embed APIs.
Monitoring Recommendations
- Enable verbose access logging on the SiYuan HTTP listener and forward logs to a centralized analytics platform.
- Track the SiYuan process version at runtime to identify hosts still running versions before v3.7.4.
- Monitor egress data volumes from SiYuan hosts to detect bulk content extraction.
How to Mitigate CVE-2026-72795
Immediate Actions Required
- Upgrade all SiYuan instances to v3.7.4 or later without delay.
- Inventory internet-exposed SiYuan deployments and restrict access to trusted networks until patching is complete.
- Rotate any credentials or secrets stored in SiYuan documents that may have been exposed while the instance was vulnerable.
Patch Information
The SiYuan maintainers addressed the flaw in v3.7.4 by enforcing publish-access checks on embedded block content within the getBlockDOMWithEmbed and getBlockDOMsWithEmbed endpoints. Details of the fix are documented in the GitHub Security Advisory GHSA-h6w7-xxcf-w2mq.
Workarounds
- Place vulnerable SiYuan instances behind an authenticating reverse proxy that restricts access to known users.
- Disable publishing of documents that contain embed queries until the upgrade to v3.7.4 is complete.
- Remove or unpublish sensitive documents from the workspace to reduce exposure if immediate patching is not feasible.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
