External risk intelligence

SiYuan Stored XSS to RCE in Attribute View.

CVE advisorySeverity: CRITICAL (CVSS 9.4)

CVE-2026-65605

SiYuan is primarily a local, personal knowledge management desktop application. While it can be used for self-hosted collaboration, it is not an internet-facing edge service, gateway, or public web application. The vulnerability requires the user to interact with a specific database view, making it a client-side execution context rather than a reachable network-facing attack surface.

Cross-site Scripting

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability exists in SiYuan software related to how it renders data within its Attribute View, potentially allowing malicious code to be executed. This issue could have serious implications if a user interacts with a compromised database cell.

Stored cross-site scripting in database cells.
Enables arbitrary command execution on user systems.
Confirm relevance and assess exposure.

Attack Path

How an attacker could exploit the issue

An attacker could exploit this vulnerability by tricking a user into viewing a specific database cell containing a crafted payload. This payload leverages a weakness in how certain HTML tags are handled when displayed, allowing the malicious script to be stored and then executed within the user's browser. If the user is accessing SiYuan via its desktop application, this script can then gain elevated privileges, potentially leading to command execution on their computer.

No authentication or specific user privilege required.
Viewing a malicious database cell renders HTML.
Leads to arbitrary command execution.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability in SiYuan's Attribute View could allow an attacker to execute arbitrary commands on a user's system. This occurs when a specially crafted Template column value is rendered as HTML without proper escaping, and the database is subsequently viewed. When supported by the advisory, this exploit can lead to arbitrary code execution.

Stored malicious scripts in database cells.
Viewing a crafted database cell.
Arbitrary command execution on the user's system.

Operational Fix

Recommended remediation, mitigation, and detection steps

SiYuan's stored cross-site scripting vulnerability, especially when combined with its desktop renderer's `nodeIntegration` capabilities, necessitates a coordinated response. Application owners responsible for SiYuan instances must first identify all deployments, determine their reachability and business criticality, and locate the accountable owner. This foundational step enables risk-based remediation planning, which may involve vendor coordination, temporary mitigations, or scheduling maintenance for an eventual fix.

Identify SiYuan instances and ownership.
Verify exposure and business criticality.
Plan remediation based on risk.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is SiYuan software?

SiYuan is a privacy-first, personal knowledge management tool that supports block-style editing and local data storage. It is often used for note-taking, journaling, and organizing information. Because it functions as a desktop application with advanced rendering capabilities, it can bridge the gap between web-based data handling and local system operations.

What does this CVE-2026-65605 vulnerability mean?

This is a stored cross-site scripting (XSS) weakness classified as CWE-79. It occurs when the software incorrectly handles HTML tags in the Attribute View of a database. If a malicious script is saved in a template column, the application may execute it when that data is displayed, rather than treating the input as plain, harmless text.

How is this vulnerability triggered?

An attacker triggers the bug by placing a crafted HTML payload into an Attribute View cell. The vulnerability specifically activates when the system fails to properly escape certain HTML tags, such as self-closing tags like image elements. It is not triggered if the data is viewed in a way that avoids rendering the malicious HTML content or if the input is safely neutralized before being stored.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal indicates that exploitation is very unlikely for most users. SiYuan is typically a personal desktop application rather than a public-facing web service. Because the vulnerability requires a user to interact with a specific database view within the application to execute the malicious script, it functions as a client-side risk rather than a remotely reachable network threat.

What should I do if I use SiYuan?

Your first step is to verify your current software version to see if it precedes v3.7.2. Locate your active instances of the application and assess how you use the Attribute View feature. Prioritize updating the software to the latest version provided by the vendor to eliminate the underlying flaw, and exercise caution when importing or viewing database content from untrusted sources.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.