Description

SiYuan versions before v3.8.4 contain a path traversal vulnerability in the setNotebookIcon endpoint that allows authenticated administrators to create arbitrary directory trees and write files outside the workspace boundary. Attackers can supply directory traversal sequences in the notebook parameter to escape the workspace data directory and write conf.json files to arbitrary locations accessible by the kernel process.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.6",
  "pubDate": "2026-09-26T14:16:45.480Z",
  "pubdate": "2026-09-26T14:16:45.480Z",
  "executiveSummary": "SiYuan versions prior to v3.8.4 are susceptible to a critical path traversal vulnerability located within the setNotebookIcon endpoint.\nThe flaw stems from insufficient sanitization of input parameters, enabling an authenticated administrator to bypass workspace directory restrictions.\nAn attacker can exploit this vulnerability by injecting directory traversal sequences into the notebook parameter, facilitating the creation of arbitrary directory structures and the unauthorized writing of files, specifically targeting conf.json configurations, at locations outside the intended workspace boundary.\nSuccessful exploitation grants the attacker the ability to influence the kernel process environment by writing files to sensitive system locations accessible by the application process.\nThis vulnerability poses a significant risk to the integrity and security of the host environment, as it allows for arbitrary file write operations.\nExploitation requires authenticated access with administrative privileges, which is a critical precondition for triggering the vulnerable endpoint.\nThe scope of impact is contingent upon the filesystem permissions of the process executing the SiYuan kernel, potentially allowing for system-level configuration tampering.",
  "technicalDetails": "The vulnerability is rooted in the improper handling of user-supplied input within the setNotebookIcon endpoint in SiYuan versions before v3.8.4. The application fails to adequately validate or sanitize the notebook parameter before utilizing it to resolve filesystem paths for icon storage.\nThe root cause is an inadequate implementation of path normalization and boundary checks. By failing to strip or reject directory traversal sequences (e.g., '../'), the application permits the concatenation of these sequences into the base path, allowing the process to traverse outside the designated workspace data directory.\nThe attack flow proceeds as follows: An authenticated administrator sends a crafted request to the setNotebookIcon endpoint. Within the request, the notebook parameter is manipulated to include traversal sequences. When the kernel processes this request, it interprets the malicious path and resolves it to a target location external to the intended workspace. The kernel then performs a file write operation to create or overwrite a conf.json file at the destination path specified by the attacker.\nThe technical impact allows the modification or creation of configuration files in arbitrary locations that are reachable by the kernel process. This is particularly dangerous as it may allow an attacker to influence the startup behavior, service configuration, or internal settings of the application by overwriting existing configuration files or creating new ones in sensitive directories.\nThe vulnerability requires the attacker to have already achieved authenticated administrator access to the SiYuan instance. The network exposure is limited to the interface where the administrative API is exposed. Because the file operations are performed by the process running the kernel, the scope of the file write is restricted only by the OS-level permissions of the user account running the SiYuan kernel.\nThe payload behavior involves the placement of specific configuration directives into a target location. By controlling the contents of a conf.json file, an attacker can potentially alter the kernel's configuration, leading to arbitrary code execution or further privilege escalation, depending on how the application consumes these configuration files during runtime."
}