CVE-2026-82234

SiYuan before v3.8.1 SSRF via DNS-Rebinding TOCTOU

HIGH
8.2
CVSS Score
Published: August 28, 2026 at 10:49 AM UTC
Updated: August 28, 2026 at 08:20 PM UTC
2 products affected across 2 vendorsSiyuanSiyuan

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Severity
HIGH8.2
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

SiYuan versions before v3.8.1 contain a server-side request forgery vulnerability in the http_request and web_fetch agent tools that perform DNS resolution only at guard time without validating the connect-time resolution. Attackers can use DNS rebinding to answer the guard resolution with a public IP and the connect resolution with a private or metadata IP, bypassing the SSRF defense to access cloud instance metadata and internal services.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 3.8.1
Affected range stops below 3.8.1, so it looks safe — our inference, not a vendor statement
v < 3.8.1
Vendor states this is fixed in 3.8.1 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.2HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-918

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