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SiYuan CVE-2026-73045

HIGH
Improper Restriction of Excessive Authentication Attempts (CWE-307)
2026-08-15 disclosure@vulncheck.com
8.7
CVSS 4.0 · Vendor: vulncheck
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Severity by source

Vendor (vulncheck) PRIMARY
8.7 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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
vuln.today AI
7.5 HIGH

Network-reachable endpoint, no credentials or user interaction required; only confidentiality is impacted - notebook contents disclosed, no integrity or availability effect.

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

Primary rating from Vendor (vulncheck).

CVSS VectorVendor: vulncheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

2
Analysis Generated
Aug 15, 2026 - 22:33 vuln.today
CVE Published
Aug 15, 2026 - 22:16 cve.org
HIGH 8.7

DescriptionCVE.org

SiYuan before 3.7.4 contains an improper restriction of excessive authentication attempts vulnerability in the authFilePublishAccess endpoint that allows unauthenticated attackers to brute-force per-notebook publish passwords. Attackers can submit unbounded password guesses without rate limiting or CAPTCHA to gain access to password-protected published notebooks.

AnalysisAI

Unauthenticated brute-force of per-notebook publish passwords is possible in SiYuan before 3.7.4 due to the complete absence of rate limiting or CAPTCHA on the authFilePublishAccess endpoint. Any network-reachable SiYuan instance with the notebook publishing feature enabled and at least one password-protected published notebook is exposed to automated credential guessing, potentially disclosing the notebook's full contents to an unauthorized party. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Identify network-exposed SiYuan instance
Delivery
Discover published notebook URL/path
Exploit
Automate password guesses to authFilePublishAccess endpoint
Execution
Recover notebook publish password
Impact
Access full contents of protected notebook

Vulnerability AssessmentAI

Exploitation Exploitation requires the SiYuan instance to be bound to a network-accessible address (not localhost-only, which is the default), the notebook publish feature to be enabled with at least one notebook configured with a per-notebook publish password, and the attacker to know or discover the target notebook's publish path. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N) is consistent with the description: network-reachable, zero prerequisites, fully automated exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker scans the internet for SiYuan instances (identifiable by default UI fingerprints on common ports) and discovers an exposed deployment. Navigating to a published notebook URL, they identify a password prompt and automate HTTP POST requests to the authFilePublishAccess endpoint, cycling through a dictionary or character-space wordlist at high throughput with no server-imposed delay, ultimately recovering the password and reading the notebook contents in full.
Remediation Upgrade to SiYuan 3.7.4 or later, which addresses the missing rate limiting on the authFilePublishAccess endpoint per the vendor advisory at https://github.com/siyuan-note/siyuan/security/advisories/GHSA-v362-968x-gp2v. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, conduct a network discovery to identify all SiYuan instances with the publishing feature enabled and assess which notebooks are password-protected and externally reachable; document the installed versions and flag any running releases prior to 3.7.4. …

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CVE-2026-73045 vulnerability details – vuln.today

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