CVE-2026-82234: SiYuan Agent Tools SSRF via DNS rebinding

CVE-2026-82234 · Severity: high · CVSS 8.2 · Published 2026-08-28

SiYuan is a popular note-taking and knowledge management application with built-in AI agent capabilities that can fetch web content on behalf of the user. A server-side request forgery vulnerability in the http_request and web_fetch agent tools allows attackers to bypass security checks and access cloud instance metadata and internal services on the network. An attacker who can influence the agent to fetch a malicious domain can gain unauthorized access to sensitive internal data and systems.

Technologies: github.com/siyuan-note/siyuan/kernel (Go), SiYuan. Vendors: Go, SiYuan.

Quick answers

Is CVE-2026-82234 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-82234 being exploited in the wild.
How severe is CVE-2026-82234?
High severity, with a CVSS score of 8.2, published 28 August 2026.
Which products and versions are affected?
github.com/siyuan-note/siyuan/kernel (Go) SEMVER:introduced=0,fixed=0.0.0-20260813142806-dd2778b70d02; SiYuan before v3.8.1.
Is there a fix for CVE-2026-82234?
Yes. github.com/siyuan-note/siyuan/kernel (Go): upgrade to 0.0.0-20260813142806-dd2778b70d02 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-82234 attacked?
It is attacked over the network.
Am I affected by CVE-2026-82234?
Check whether you run github.com/siyuan-note/siyuan/kernel (Go) or SiYuan at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/siyuan-note/siyuan/kernel (Go): upgrade to 0.0.0-20260813142806-dd2778b70d02 or later
    go get github.com/siyuan-note/siyuan/kernel@v0.0.0-20260813142806-dd2778b70d02

Technical details

This is a server-side request forgery (CWE-918) vulnerability caused by a time-of-check-to-time-of-use (TOCTOU) issue in DNS resolution. The http_request and web_fetch agent tools perform DNS resolution and validation only at "guard time" using CheckHostSSRF, which blocks private/loopback IP addresses. However, the actual connection phase performs a second, independent DNS resolution via the default net.Dialer without any private IP validation. An attacker can exploit this with DNS rebinding: answer the guard-time resolution with a public IP (bypassing the check) and the connect-time resolution with a private or metadata IP (169.254.169.254), reaching cloud metadata endpoints and internal services. The vulnerability affects all versions up to and including v3.8.0; v3.8.1 contains the fix. Attack requires network access and the ability to influence the agent into fetching an attacker-controlled domain (e.g., via prompt injection).

Affected products

  • SiYuan SiYuan before v3.8.1

Identifiers

  • CVE-2026-82234
  • GHSA-x8gv-g2g3-65fj
  • GO-2026-6657

Timeline

  • 2026-08-13: disclosed: Reported to SiYuan team
  • 2026-08-28: advisory: CVE-2026-82234 published
  • 2026: patched: Fixed in v3.8.1

References

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