SiYuan 3.7.3 Cross-Site WebSocket Hijacking via network proxy

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

SiYuan versions before 3.7.4 contain a cross-site WebSocket hijacking vulnerability in the admin-only /ws/network/proxy endpoint that explicitly disables origin validation by setting CheckOrigin to unconditionally return true. Attackers can craft malicious webpages that establish WebSocket connections to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to attacker-chosen targets, enabling authenticated network pivoting through the victim's machine.

Source published

17 Aug 2026 11:04:37 UTC

Source modified

28 Aug 2026 13:45:55 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS 3.1 · 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

SiYuan versions before 3.7.4 contain a cross-site WebSocket hijacking vulnerability in the admin-only /ws/network/proxy endpoint that explicitly disables origin validation by setting CheckOrigin to unconditionally return true. Attackers can craft malicious webpages that establish WebSocket connections to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to attacker-chosen targets, enabling authenticated network pivoting through the victim's machine.

Source published

Aug 17, 2026, 11:04:37 AM (timezone not stated)

Source modified

Aug 28, 2026, 1:45:55 PM (timezone not stated)

Observed here

9 Nov 2026 15:11:46 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 4.0 · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N

SiYuan versions before 3.7.4 contain a cross-site WebSocket hijacking vulnerability in the admin-only /ws/network/proxy endpoint that explicitly disables origin validation by setting CheckOrigin to unconditionally return true. Attackers can craft malicious webpages that establish WebSocket connections to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to attacker-chosen targets, enabling authenticated network pivoting through the victim's machine.

Source published

17 Aug 2026 11:16:40 UTC

Source modified

28 Aug 2026 16:18:24 UTC

Observed here

25 Oct 2026 15:19:09 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 7.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

**High** ## Package gomod `github.com/siyuan-note/siyuan/kernel` ## Affected versions 3.7.3 ## Patched versions *(none yet — leave blank until a fix is released)* ## Description ### Summary `/ws/network/proxy` is an admin-only WebSocket forward-proxy endpoint (target URL and headers fully attacker-specifiable via query parameters). Its `websocket.Upgrader` explicitly overrides `CheckOrigin` to unconditionally return `true` — disabling the origin validation that the `gorilla/websocket` library otherwise enforces **by default**. WebSocket handshake requests are not subject to CORS preflight at all (unlike `fetch`/XHR), so origin validation for WebSocket endpoints has to be done deliberately by the server; here it has been deliberately turned *off* instead. Combined with the endpoint's own query-parameter-driven proxy target, this is a textbook Cross-Site WebSocket Hijacking (CSWSH) primitive on a capability that amounts to an authenticated network pivot through the SiYuan kernel process. ### Details ```go // kernel/api/network.go:501 upgrader := websocket.Upgrader{ CheckOrigin: func(r *http.Request) bool { return true }, } clientConn, upgradeErr := upgrader.Upgrade(c.Writer, c.Request, upgradeHeaders) ``` Route registration (admin-role-gated): ```go // kernel/api/router.go:614 ginServer.Handle("GET", "/ws/network/proxy", model.CheckAuth, model.CheckAdminRole, wsProxy) ``` The proxy target is fully attacker-controllable via query parameters, decoded and dialed directly: ```go // kernel/api/network.go:348 func parseForwardProxyParams(c *gin.Context) (parsedURL *url.URL, headers *http.Header, timeout time.Duration, err error) { uParam := c.Query("u") ... uBytes, decErr := base64.RawURLEncoding.DecodeString(uParam) ... parsedURL, err = url.ParseRequestURI(string(uBytes)) ... hParam := c.Query("h") // optional forwarded headers, also base64-encoded ``` A malicious webpage can construct, entirely from JavaScript with no special access: ```js new WebSocket("ws://127.0.0.1:6806/ws/network/proxy?u=" + base64url(attackerChosenTargetURL)); ``` WebSocket handshake requests are GET requests carrying ambient cookies exactly like any other cross-site navigation, and are not covered by CORS preflight protections at all, this is a distinct attack surface from ordinary `fetch`/XHR-based CSRF, and easy to overlook precisely because the usual CORS mental model doesn't apply to it. Whether this is currently exploitable in a given browser depends on the same session-cookie `SameSite` configuration already covered by a separate report on this repository (no explicit `SameSite` is set on the session cookie), but even where that provides incidental protection today, the explicit `CheckOrigin: func(r *http.Request) bool { return true }` override removes a defense-in-depth layer that would otherwise exist automatically from the WebSocket library's own safe default, and is worth fixing independently of the cookie-attribute question. ### Impact If reachable (dependent on browser/cookie-attribute behavior at time of exploitation, as above), a malicious website visited by a user with an active, admin-privileged SiYuan session could open a WebSocket connection to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to an attacker-chosen target, effectively an authenticated SSRF/network-pivot primitive, using the victim's own machine and any network position it has (e.g., internal/localhost-only services on the victim's LAN that aren't reachable from the public internet), entirely via a drive-by visit to an unrelated website while SiYuan happens to be running. ### PoC No live browser PoC was run for this report, this is a code-level confirmation that the `CheckOrigin` override exists and unconditionally returns `true`, combined with tracing the fully attacker-controlled proxy-target construction. I also checked whether the other WebSocket-adjacent endpoints (`/ws/plugin/rpc`, `/ws/broadcast`) share this issue: they use a different WebSocket library (`gws`, not `gorilla/websocket`) with a different upgrade code path I have not independently verified for its own origin-checking defaults, flagging this as worth a follow-up check by your team rather than claiming it applies there too. ``` ## Affected products | Field | Value | |---|---| | Ecosystem | **Go** | | Package name | `github.com/siyuan-note/siyuan/kernel` | | Affected versions | `<= 3.7.3` (confirmed present in 3.7.3; maintainers should confirm lower bound) | | Patched versions | *(none yet — leave blank until a fix is released)* | ## Severity | Field | Value | |---|---| | Vector string | `CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:N/A:N` | | Score | **5.5 (Medium)**, reflecting that real-world exploitability depends on the co-occurring session-cookie `SameSite` question (also separately reported) and requires a victim with an active admin session to visit an attacker-controlled page (`AC:H`, `UI:R`); I'd expect this to be scored higher by your team if you determine the cookie/browser-behavior precondition is reliably met, since the underlying capability (network pivot through the kernel process) is significant. | ## Weaknesses (CWE) - **CWE-346** — Origin Validation Error (primary — this is the textbook CWE for CSWSH) - **CWE-352** — Cross-Site Request Forgery (the broader category this specific WebSocket variant falls under) - **CWE-918** — Server-Side Request Forgery (secondary — the resulting capability once a connection is hijacked) - ``` ## Suggested Fix Replace `CheckOrigin: func(r *http.Request) bool { return true }` with a real check — validate the `Origin` header against the expected local/loopback origin (or the configured workspace's own address), mirroring how `IsLoopbackCallback`-style validation is already done correctly elsewhere in this codebase (e.g. the MCP OAuth client's loopback-callback check). Also worth auditing the `gws`-based WebSocket endpoints (`/ws/plugin/rpc`, `/ws/broadcast`) for their own origin-validation defaults, since I did not verify those independently.

Source published

2 Oct 2026 22:46:18 UTC

Source modified

7 Oct 2026 17:55:42 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:N/I:N/A:N

Publisher rating · LOW

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-3cc2-h3v6-rqpq. This link is maintained to preserve external references. ## Original Description SiYuan versions before 3.7.4 contain a cross-site WebSocket hijacking vulnerability in the admin-only /ws/network/proxy endpoint that explicitly disables origin validation by setting CheckOrigin to unconditionally return true. Attackers can craft malicious webpages that establish WebSocket connections to this endpoint and direct the SiYuan kernel process to proxy arbitrary network traffic to attacker-chosen targets, enabling authenticated network pivoting through the victim's machine.

Source published

17 Aug 2026 12:32:21 UTC

Source modified

2 Oct 2026 23:00:17 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Publisher rating · LOW

SiYuan: Cross-Site WebSocket Hijacking on the admin-only network proxy endpoint (`/ws/network/proxy`) via explicit `CheckOrigin: true` bypass in github.com/siyuan-note/siyuan/kernel

Source published

7 Oct 2026 14:10:14 UTC

Source modified

7 Oct 2026 17:45:13 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.