CVE-2026-82234Public exploitNetwork attack vectorHinoki check available

Internal service access via DNS-rebinding SSRF

Published Aug 28, 2026 · Updated Aug 28, 2026

SSRF in SiYuan's http_request and web_fetch agent tools before 3.8.1 allows remote attackers to access internal services via DNS rebinding. CheckHostSSRF resolves the supplied hostname during validation, but the default transport resolves it again without a connect-time private-address check. Exploitation requires an agent or MCP client to fetch an attacker-controlled domain; rebinding then exposes cloud metadata and internal service responses.

CVSS severity8.4
High
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

SSRF in SiYuan's http_request and web_fetch agent tools before 3.8.1 allows remote attackers to access internal services via DNS rebinding. CheckHostSSRF resolves the supplied hostname during validation, but the default transport resolves it again without a connect-time private-address check. Exploitation requires an agent or MCP client to fetch an attacker-controlled domain; rebinding then exposes cloud metadata and internal service responses.

The record

CVE
CVE-2026-82234
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-350, CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 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 <3.8.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.8.1

Published CVSS scores

8.4VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N
8.2GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-350Reliance on Reverse DNS Resolution
CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

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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