SiYuan Agent Tools SSRF via DNS-Rebinding TOCTOU (Bypass of CheckHostSSRF)

{
  "id": "afa627ddfbc60dc1a8735ad8c801018151ac38f92cff6bcf20ddcb0c12315275",
  "url": "https://osv.dev/vulnerability/GHSA-x8gv-g2g3-65fj",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SiYuan Agent Tools SSRF via DNS-Rebinding TOCTOU (Bypass of CheckHostSSRF)",
    "summary": "# Security Advisory — SiYuan Agent Tools SSRF via DNS-Rebinding TOCTOU (Bypass of `CheckHostSSRF`) | Field | Value | |---|---| | **Disclosed by** | joysinleung (`joysinleung@gmail.com`) | | **Report date** | 2026-08-13 | | **Product** | SiYuan (思源笔记) — `siyuan-note/siyuan` | | **Go module** | `github.com/siyuan-note/siyuan/kernel` | | **Affected versions** | `<= 3.8.0` (latest release at report time; dynamically verified on v3.8.0) | | **Patched versions** | 3.8.1 | | **Component** | `kernel/util/httprequest.go` (`CheckHostSSRF`), `kernel/mcp/tools/http_request.go`, `kernel/util/webfetch.go`, `kernel/util/net.go` (`SSRFSafeDialer`) | | **Relationship to prior advisory** | **Incomplete-fix variant of GHSA-rg26-cg95-gq6p** (SSRF main-vector remediation). See §Relationship. | | **EPSS (exploitation probability)** | Low–Moderate. Requires the attacker to influence an AI Agent / MCP client into fetching an attacker-controlled domain (prompt-injection scenario documented by the tool itself). | | **KEV (CISA Known Exploited)** | No (not listed in CISA KEV at report time). | | **Default-config reachable** | **Yes** — exploitable under *both* `SafeMode` on and off; only requires the agent `http_request` / `web_fetch` tool to be reachable (default AI tooling). | --- ## Summary SiYuan's AI Agent tools `http_request` (`util.HTTPRequest`) and `web_fetch` (`util.WebFetch`) are the only SSRF gate for outbound requests from the kernel. That gate is `CheckHostSSRF`, which performs a **single ",
    "evidence": "osv:GHSA-x8gv-g2g3-65fj",
    "products": [
      {
        "name": {
          "value": "github.com/siyuan-note/siyuan/kernel",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.0.0-20260813142806-dd2778b70d02",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-x8gv-g2g3-65fj",
      "aliases": [
        "CVE-2026-82234",
        "GHSA-x8gv-g2g3-65fj",
        "GO-2026-6657"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.0.0-20260813142806-dd2778b70d02"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/siyuan-note/siyuan/kernel",
            "purl": "pkg:golang/github.com/siyuan-note/siyuan/kernel",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-x8gv-g2g3-65fj/GHSA-x8gv-g2g3-65fj.json"
          }
        }
      ],
      "modified": "2026-10-07T17:55:46.332710273Z",
      "provider": "osv",
      "references": [
        "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-x8gv-g2g3-65fj",
        "https://github.com/siyuan-note/siyuan/commit/dd2778b70d020b15491ef7418f5f63214583cd63",
        "https://github.com/siyuan-note/siyuan",
        "https://github.com/siyuan-note/siyuan/releases/tag/v3.8.1"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-918"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-02T23:17:16Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-82234",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 97128,
  "published_at": "2026-10-02T23:17:16+00:00"
}

{
  "id": "563985a882901e14cf57de012e624f4c98fc780ae2e7158eabd3d9ae28a6d3da",
  "url": "https://osv.dev/vulnerability/GO-2026-6657",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "SiYuan Agent Tools SSRF via DNS-Rebinding TOCTOU (Bypass of CheckHostSSRF) in github.com/siyuan-note/siyuan/kernel",
    "summary": "SiYuan Agent Tools SSRF via DNS-Rebinding TOCTOU (Bypass of CheckHostSSRF) in github.com/siyuan-note/siyuan/kernel",
    "evidence": "osv:GO-2026-6657",
    "products": [
      {
        "name": {
          "value": "github.com/siyuan-note/siyuan/kernel",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "0.0.0-20260813142806-dd2778b70d02",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "GO-2026-6657",
      "aliases": [
        "CVE-2026-82234",
        "GHSA-x8gv-g2g3-65fj",
        "GO-2026-6657"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0.0.0-20260813142806-dd2778b70d02"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/siyuan-note/siyuan/kernel",
            "purl": "pkg:golang/github.com/siyuan-note/siyuan/kernel",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://vuln.go.dev/ID/GO-2026-6657.json"
          },
          "ecosystem_specific": {}
        }
      ],
      "modified": "2026-10-07T17:55:46.332710273Z",
      "provider": "osv",
      "references": [
        "https://github.com/siyuan-note/siyuan/security/advisories/GHSA-x8gv-g2g3-65fj",
        "https://github.com/siyuan-note/siyuan/commit/dd2778b70d020b15491ef7418f5f63214583cd63",
        "https://github.com/siyuan-note/siyuan/releases/tag/v3.8.1"
      ],
      "provider_metadata": {
        "url": "https://pkg.go.dev/vuln/GO-2026-6657",
        "review_status": "UNREVIEWED"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-82234",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 97129,
  "published_at": "2026-10-07T14:10:14+00:00"
}