siyuan-note SiYuan up to 3.8.1 /api/system/uiproc denial of service

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.3$0-$5k0.82-

Summaryinfo

A vulnerability was found in siyuan-note SiYuan up to 3.8.1. It has been rated as problematic. Impacted is an unknown function of the file /api/system/uiproc. This manipulation causes denial of service. This vulnerability is registered as CVE-2026-85581. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability classified as problematic was found in siyuan-note SiYuan up to 3.8.1. Affected by this vulnerability is an unknown function of the file /api/system/uiproc. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-85581 since 09/04/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 3.8.2 eliminates this vulnerability.

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Vendor

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Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: SiYuan 3.8.2

Timelineinfo

09/04/2026 Advisory disclosed
09/04/2026 +0 days CVE reserved
09/04/2026 +0 days VulDB entry created
09/04/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-85581 (🔒)
GCVE (CVE): GCVE-0-2026-85581
GCVE (VulDB): GCVE-100-398755

Entryinfo

Created: 09/04/2026 13:57
Changes: 09/04/2026 13:57 (76)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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