SiYuan Vulnerable to Arbitrary File Read via File Copy Functionality
Date: 2026-01
Affected: go/github.com/siyuan-note/siyuan/kernel
Attack vector: data-exfiltration
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-23851
CWE: CWE-22

### Summary The SiYuan Note application (v3.5.3) contains a logic vulnerability in the /api/file/globalCopyFiles endpoint. The function allows authenticated users to copy files from any location on the server's filesystem into the application's workspace without proper path validation ### Details The vulnerability exists in the api/file.go source code. The function globalCopyFiles accepts a list of source paths (srcs) from the JSON request body. While the code checks if the source file exists using filelock.IsExist(src), it fails to validate whether the source path resides within the authorized workspace directory. ``` func globalCopyFiles(c *gin.Context) { // ... srcsArg := arg["srcs"].([]interface{}) for _, src := range srcs { if !filelock.IsExist(src) { ... } if err := filelock.Copy(src, dest); err != nil { ... } } } ``` ### PoC The following steps demonstrate how to exfiltrate the /etc/passwd file. 1. The attacker sends a request to copy the system file /etc/passwd to the root of the application workspace (/). <img width="1537" height="357" alt="image" src="https://github.com/user-attachments/assets/7c8e5fe8-f609-4263-8685-eedf3cf22400" /> 2. The attacker downloads the copied file using the standard file retrieval API, which now treats the system file as a legitimate workspace asset. <img width="1549" height="588" alt="image" src="https://github.com/user-attachments/assets/37cac3dd-d9a9-4191-92ea-16f0424c73e1" /> <im


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