CVE-2026-85581

SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration

8.7 High

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.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.57%Up 0.3 points since Sep 5, 2026

What each source reports

CVE List Score used8.7

SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration

Record: CVE-2026-85581
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

EUVDEUVD-2026-710048.7

Record: EUVD-2026-71004
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-4qv4-f447-c9m28.7

SiYuan before v3.8.2 contains a denial of service vulnerability in the unauthenticated /api...

Record: GHSA-4qv4-f447-c9m2
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

NVD8.7

Record: CVE-2026-85581
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/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
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Updated: 2026-11-02

OSV8.7

SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration

Record: CVE-2026-85581
CVSS 4.0: 8.7 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness: CWE-770
Updated: 2026-11-02

Affected products

siyuan-note siyuan

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-85581 is a high vulnerability (CVSS 8.7) in Siyuan-note Siyuan, published September 4, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.57%, the 47th percentile. No source names a fixed version.