CVE-2026-72809
HighCVSS 8.0Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end.
Risk Assessment
The risk includes the possibility of remote unauthorized access to sensitive endpoints, which could lead to unauthorized actions within the system.
Recommendation
It is recommended to update SiYuan to version v3.7.4 or later and configure trusted proxies and inject authentication tokens in the reverse proxy.
Other vulnerabilities in SiYuan
See all- CVE-2026-103763Medium
SiYuan before v3.8.5 contains an information disclosure vulnerability that allows read-only publish readers to learn metadata of publish-excluded documents through the getNotebookInfo endpoint. Attackers, including anonymous visitors when no reader password is set, can query publish-visible notebooks to obtain document count, size and modification timestamps of hidden documents.
- CVE-2026-100636High
SiYuan versions before v3.8.4 contain a path traversal vulnerability in the exportBrowserHTML endpoint that allows authenticated administrators to write arbitrary HTML content to index.html outside the workspace directory. Attackers can supply a folder parameter with directory traversal sequences to escape the export directory and overwrite index.html in any pre-existing kernel-writable location, enabling stored XSS or workspace defacement.
- CVE-2026-92986High
SiYuan before 3.8.4 renders document titles as HTML in the backlink dock tree without escaping markup characters. Attackers can set malicious titles through the rename API or crafted notebooks to execute scripts in the Electron renderer with access to child_process for command execution.
- CVE-2026-92985High
SiYuan versions before 3.8.4 fail to escape bookmark labels imported from notebook files when rendering them in the dock tree. Attackers can craft malicious .sy notebook files with unescaped HTML in bookmark attributes that execute scripts in the Electron renderer with access to child_process for command execution.
- CVE-2026-45371High
SiYuan is a knowledge management system that prior to version 3.7.0 had security vulnerabilities related to 8 ungated APIs that could modify configuration and SQL index. Users with a valid JWT token could access these APIs, leading to unauthorized changes to server state.
- CVE-2026-41894High
SiYuan is an open-source personal knowledge management system. Prior to 3.6.5, the fix for CVE-2026-30869 only added a denylist check but did not address the root cause – a redundant url.PathUnescape() call in serveExport(). An authenticated attacker can use double URL encoding to traverse directories and read arbitrary workspace files including the full SQLite database, kernel log, and all user documents.
- CVE-2026-84803Critical
SiYuan before version 3.8.2 contains a stored cross-site scripting vulnerability in asset serving due to an incomplete extension blocklist that misses script-capable file types. Attackers can upload files with extensions like .xht, .ehtml, .xsl, .xbl, or .rdf that resolve to executable media types and execute JavaScript to steal API tokens and compromise workspaces.
- CVE-2026-77086Critical
SiYuan before v3.7.4 fails to validate the packageName parameter in Bazaar install and uninstall endpoints, allowing authenticated administrators to perform path traversal. Attackers with admin access can write arbitrary files or recursively delete directories by supplying crafted packageName values.
- CVE-2026-74800Critical
SiYuan before v3.7.4 fails to set Content-Disposition and X-Content-Type-Options headers when serving arbitrary file assets, allowing stored cross-site scripting attacks. Authenticated attackers can upload HTML files as assets and execute scripts with full kernel API access when the workspace owner opens the asset link.
- CVE-2026-74799Critical
SiYuan before 3.7.4 registers Go net/http/pprof debug endpoints including heap and goroutine dumps without authentication when --mode flag is not set to exactly prod. Attackers can access /debug/pprof/heap and related endpoints to extract in-memory secrets including AccessAuthCode and AI provider API keys.
Original NVD description (English source)
SiYuan versions <= v3.7.2 (patched in v3.7.4) contain an authentication bypass vulnerability in the kernel's CheckAuth function, which grants the administrator role (RoleAdministrator) to any request whose RemoteAddr is loopback (127.0.0.1) for a specific set of endpoints (including /api/system/exit, getNetwork, getWorkspaceInfo, /assets/*, and /export/*). These localhost bypasses sit outside the access auth code gate, so they apply even when an access auth code is configured. Because the fixed-port reverse proxy forwards requests to the kernel over loopback without injecting an authentication token and does not configure trusted proxies, a request forwarded through this proxy reaches the kernel with RemoteAddr = 127.0.0.1. If the fixed-port proxy is bound to a network interface, this could allow a remote unauthenticated attacker to obtain admin access on the affected endpoints; however, per the advisory this remote forwarding behavior was established only by code inspection and was not reproduced end-to-end.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

