CVE-2026-85581: SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration
SiYuan before v3.8.2 contains a denial of service vulnerability in the unauthenticated /api/system/uiproc endpoint that accepts and retains attacker-controlled process identifiers without size limits or authentication. Attackers can send repeated requests with unique identifiers to exhaust process memory and degrade service availability.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed?
SiYuan versions before v3.8.2 are affected where the unauthenticated /api/system/uiproc endpoint is reachable by an attacker. Because the endpoint requires no authentication, an unauthenticated remote attacker can trigger the issue.
What does exploitation require?
An attacker only needs to send repeated requests to /api/system/uiproc using unique attacker-controlled process identifiers. No privileges or user interaction are required.
What is the impact of a successful attack?
The endpoint retains supplied process identifiers without size limits, allowing repeated requests to consume process memory. This can degrade availability or cause denial of service; the provided data does not indicate confidentiality or integrity impact.
How can I determine whether an instance is affected?
Check the installed SiYuan version and whether it is earlier than v3.8.2. Also determine whether the /api/system/uiproc endpoint is reachable from attacker-controlled networks, since exposure to that endpoint enables exploitation.