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

Source: https://junglewise.ai/threats/cve-2026-82234-siyuan-agent-tools-ssrf-via-dns-rebinding  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-28. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-siyuan-note-siyuan-kernel), [SiYuan](https://junglewise.ai/threats/technologies/siyuan). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [SiYuan](https://junglewise.ai/threats/vendors/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

  ```sh
  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

- [https://github.com/siyuan-note/siyuan/security/advisories/GHSA-x8gv-g2g3-65fj](https://github.com/siyuan-note/siyuan/security/advisories/GHSA-x8gv-g2g3-65fj)
- [https://www.vulncheck.com/advisories/siyuan-before-3.8.1-ssrf-via-dns-rebinding-toctou](https://www.vulncheck.com/advisories/siyuan-before-3.8.1-ssrf-via-dns-rebinding-toctou)

## Related threats

- [SiYuan path traversal in web fetch](https://junglewise.ai/threats/cve-2026-126776-siyuan-3-7-0-before-3-8-10-on-windows-contains-a-path-traversal)
- [SiYuan publish filter information disclosure in local storage](https://junglewise.ai/threats/go-2026-6836-siyuan-the-publish-filter-for-local-storage-returns-the-7f022e62)
- [SiYuan path traversal via GLOBALROOT alias bypass](https://junglewise.ai/threats/cve-2026-118680-siyuan-3-8-7-through-3-8-8-fails-to-normalize-windows-globalroot)
- [SiYuan SQL injection in history search](https://junglewise.ai/threats/cve-2026-116170-siyuan-before-v3-8-7-contains-an-sql-injection-vulnerability)
- [SiYuan cross-site scripting in /check-auth redirect](https://junglewise.ai/threats/cve-2026-116167-siyuan-from-2-9-0-before-3-8-7-contains-a-cross-site-scripting)