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CVE-2026-85581— SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration

Quick assessment

Affected
siyuan-note siyuan
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SiYuan是SiYuan团队开源的一个以隐私为先的个人知识管理系统。 SiYuan 3.8.2之前版本存在资源管理错误漏洞，该漏洞源于未认证的/api/system/uiproc端点接受并保留攻击者控制的进程标识符且无大小限制或身份验证，可能导致攻击者发送重复请求耗尽进程内存，降低服务可用性。

CVSS 7.5 · High EPSS 0.57% · P47

Possible ATT&CK Techniques 1 AI

T1027 · Obfuscated Files or Information

Affected Version Matrix 2

VendorProduct Version RangeStatus
siyuan-note siyuan < 3.8.2 affected
3.8.2 unaffected
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I. Basic Information for CVE-2026-85581

Vulnerability Information
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Vulnerability Title
SiYuan before v3.8.2 Denial of Service via unauthenticated UI-process registration
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5
Vulnerability Title
SiYuan 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
SiYuan是SiYuan团队开源的一个以隐私为先的个人知识管理系统。 SiYuan 3.8.2之前版本存在资源管理错误漏洞，该漏洞源于未认证的/api/system/uiproc端点接受并保留攻击者控制的进程标识符且无大小限制或身份验证，可能导致攻击者发送重复请求耗尽进程内存，降低服务可用性。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 0 ~ 3.8.2 -

II. Public POCs for CVE-2026-85581

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III. Intelligence Information for CVE-2026-85581

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Vendor Advisories for CVE-2026-85581 (2)

Same Patch Batch · siyuan-note · 2026-09-04 · 8 CVEs total

CVE-2026-85584 7.5 HIGH SiYuan before v3.8.2 Denial of Service via Auth Throttle
CVE-2026-85585 7.5 HIGH SiYuan before v3.8.2 Unbounded Memory Consumption via ControlConcurrency
CVE-2026-85578 6.5 MEDIUM SiYuan through 3.8.1 Authorization Bypass via getFile
CVE-2026-85583 6.5 MEDIUM SiYuan before v3.8.2 Path Traversal via symlink in file API
CVE-2026-85582 6.5 MEDIUM SiYuan before v3.8.2 Unbounded Session Creation via Basic Auth
CVE-2026-85580 6.5 MEDIUM SiYuan before v3.8.2 Path Guard Bypass via Case Mismatch
CVE-2026-85579 4.3 MEDIUM SiYuan before v3.8.2 Information Disclosure via undoState

IV. Related Vulnerabilities

Same product: siyuan
Same vendor: siyuan-note
Same weakness: CWE-770