CVE-2026-100634

SiYuan before v3.8.4 Missing Authorization via siyuan-send-windows

MEDIUM
4.7
CVSS Score
Published: September 26, 2026 at 01:23 PM UTC
Updated: October 8, 2026 at 04:16 PM UTC
2 products affected across 2 vendorsSiyuanSiyuan

Using siyuan by siyuan-note?

Get instant alerts when new vulnerabilities affect siyuan - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM4.7
Exploit prediction
EPSS 0.6%
SSVC
PoC

Description

SiYuan before v3.8.4 does not validate the sender or restrict recipients in the 'siyuan-send-windows' IPC handler of the Electron main process (app/electron/main.js). The handler ignores event.sender and forwards any received payload to every BrowserWindow returned by BrowserWindow.getAllWindows(), including windows belonging to other opened workspaces. A renderer connected to an attacker-controlled remote kernel can therefore send {cmd: "lockscreenByMode"} and have it delivered across the workspace boundary; a sibling workspace window whose lockScreenMode is set to 1 invokes lockScreen(). Repeated messages allow the remote workspace to repeatedly lock unrelated local workspace windows, causing a limited denial of service. No confidentiality, integrity, or code-execution impact was observed.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.8.4
Affected range stops below 3.8.4, so it looks safe — our inference, not a vendor statement
0 ≤ v < 3.8.40
Vendor states this is fixed in 3.8.4 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.7MEDIUMVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-862

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card