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GHSA-3g9h-9hp4-654v
No affected components available
Summary
The SiYuan kernel WebSocket server accepts unauthenticated connections when a specific “auth keepalive” query parameter is present. After connection, incoming messages are parsed using unchecked type assertions on attacker-controlled JSON.
A remote attacker can send malformed messages that trigger a runtime panic, potentially crashing the kernel process and causing denial of service.
Details
1. Authentication Bypass via Keepalive Query
Unauthenticated connections are accepted if the request URI matches a specific pattern intended for an authentication page keepalive.
File: kernel/server/serve.go
if !authOk {
authOk = strings.Contains(s.Request.RequestURI, "/ws?app=siyuan") &&
strings.Contains(s.Request.RequestURI, "&id=auth&type=auth")
}
2. Unsafe Type Assertions on Untrusted Input
Incoming JSON messages are parsed into a generic map and fields are accessed without validation.
File: kernel/server/serve.go
cmdStr := request["cmd"].(string)
cmdId := request["reqId"].(float64)
param := request["param"].(map[string]interface{})
Malformed or missing fields trigger a runtime panic. The handler does not implement local panic recovery, allowing crashes to propagate.
PoC
Step 1 — Prepare workspace directory
mkdir -p ./workspace
Step 2 — Run SiYuan container
docker run -d \
-p 6806:6806 \
-e SIYUAN_ACCESS_AUTH_CODE_BYPASS=true \
-v $(pwd)/workspace:/siyuan/workspace \
b3log/siyuan \
--workspace=/siyuan/workspace
Service becomes reachable at http://127.0.0.1:6806
Step 3 — Confirm service availability
Open in browser:
http://127.0.0.1:6806
Step 4 — Connect to unauthenticated WebSocket endpoint
ws://127.0.0.1:6806/ws?app=siyuan&id=auth&type=auth
This connection is accepted without credentials.
Step 5 — Send malformed payload
Payload:
{}
Step 6 — Observe behavior
Monitor container logs:
docker logs -f <container_id>
Impact
An unauthenticated attacker with network access can repeatedly crash the kernel, causing persistent denial of service.
Impact is highest when the service is exposed beyond localhost (e.g., Docker deployments, reverse proxies, LAN access, or public hosting).
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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