The flaw is an authorization omission in the IPC interface of SiYuan prior to version 3.8.4. Remote kernel renderers can call certain clipboard read commands (clipboardReadMathML, clipboardReadOffice, clipboardReadWPS) with matching plaintext, causing the renderer to retrieve the corresponding native clipboard format from the host. As a result, any MathML formulas, Office bytes, or WPS bytes that a user has copied to the clipboard can be read by an attacker who can inject remote renderer content. The content can include sensitive formulas or documents, leading to confidentiality compromise but not to arbitrary code execution or denial of service. The weakness is a classic information disclosure (CWE‑200).

The vulnerability affects SiYuan note‑taking application versions earlier than 3.8.4 for all platforms supported by the IPC interface. The SIYuan application exposes insecure IPC handlers that remote kernel renderers can exploit when the user is using the application.

The CVSS score of 8.6 marks this vulnerability as high severity, indicating that the compromise could expose sensitive clipboard content. An exact EPSS score is not available, so the current exploitation probability is unknown. The vulnerability is not yet listed in CISA’s KEV catalog. The likely attack vector requires an attacker to control content in a remote‑kernel renderer that is capable of sending IPC commands; such control could be achieved by exploiting a malicious web page or plugin that is loaded within the application. Once the renderer is compromised, the attacker can invoke the insecure clipboard read commands during a user paste operation to fetch MathML, Office, or WPS data from the host clipboard.