CVE-2026-74903Public exploitNetwork attack vector

Authenticated admin-only endpoint access via missing role check

Published Aug 18, 2026 · Updated Aug 18, 2026

Improper authorization in SiYuan before 3.7.4 allows remote authenticated users to access an admin-only DOM transformation endpoint. In kernel/api/router.go, POST /api/lute/spinBlockDOM is registered with CheckAuth but not the CheckAdminRole and CheckReadonly middleware used by sibling endpoint /api/lute/html2BlockDOM, and spinBlockDOM() passes the caller-supplied dom string to luteEngine.SpinBlockDOM without a size limit. Any authenticated RoleEditor or RoleReader session can reach the handler, and oversized requests can serialize and stall only that endpoint through ControlConcurrency's per-path mutex; published scoring limits the confirmed impact to low integrity.

CVSS severity5.3
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in SiYuan before 3.7.4 allows remote authenticated users to access an admin-only DOM transformation endpoint. In kernel/api/router.go, POST /api/lute/spinBlockDOM is registered with CheckAuth but not the CheckAdminRole and CheckReadonly middleware used by sibling endpoint /api/lute/html2BlockDOM, and spinBlockDOM() passes the caller-supplied dom string to luteEngine.SpinBlockDOM without a size limit. Any authenticated RoleEditor or RoleReader session can reach the handler, and oversized requests can serialize and stall only that endpoint through ControlConcurrency's per-path mutex; published scoring limits the confirmed impact to low integrity.

The record

CVE
CVE-2026-74903
Published
Aug 18, 2026
Updated
Aug 18, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-400, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.7.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.7.4

Published CVSS scores

5.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
4.3VulnCheckCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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