{
  "canonical_id": "caddy--CVE-2026-27589",
  "system_id": "caddy",
  "display_name": "Caddy",
  "category": "servers",
  "advisory_mode": "server",
  "title": "Caddy is vulnerable to cross-origin config application via local admin API /load ",
  "summary": "commit: e0f8d9b2047af417d8faf354b675941f3dac9891 (as-of 2026-02-04)\nchannel: GitHub security advisory (per SECURITY.md)\n\n## summary\n\nThe local caddy admin API (default listen `127.0.0.1:2019`) exposes a state-changing `POST /load` endpoint that replaces the entire running configuration.\n\nWhen origin enforcement is not enabled (`enforce_origin` not configured), the admin endpoint accepts cross-origin requests (e.g., from attacker-controlled web content in a victim browser) and applies an attacker-supplied JSON config. this can change the admin listener settings and alter HTTP server behavior without user intent.\n\n## Severity\n\nMedium\n\nJustification:\n- The attacker can apply an arbitrary caddy config (integrity impact) by driving a victim\u2019s local admin API.\n- Exploitation requires a victim running caddy with the admin API enabled and visiting an attacker-controlled page (or otherwise issuing the request from an untrusted local client).\n\n## Affected component\n\n- `caddyconfig/load.go: adminLoad.handleLoad` (`/load` admin endpoint)\n- Pinned callsite: https://github.com/caddyserver/caddy/blob/e0f8d9b2047af417d8faf354b675941f3dac9891/caddyconfig/load.go#L73\n\n## Reproduction\n\nAttachment: `poc.zip` (integration harness) with canonical and control runs.\n\n```bash\nunzip -q -o poc.zip -d poc\ncd poc/poc-F-CADDY-ADMIN-LOAD-001\nmake test\n```\n\nExpected output (excerpt):\n\n```\n[CALLSITE_HIT]: adminLoad.handleLoad\n[PROOF_MARKER]: http_code=200 admin_moved=true response_pwned=true\n```\n\nControl output (excerpt):\n\n```\n[NC_MARKER]: http_code=403 load_blocked=true admin_moved=false response_pwned=false\n```\n\n## Impact\n\nAn attacker can replace the running caddy configuration via the local admin API. Depending on the deployed configuration/modules, this can:\n- Change admin listener settings (e.g., move the admin listener to a new address)\n- Change HTTP server behavior (e.g., alter routes/responses)\n\n## Suggested remediation\n\nEnsure cross-origin web content cannot trigger `POST /load` on the local admin API by default, for example by:\n- Enabling origin enforcement by default for unsafe methods, and/or\n- Requiring an unguessable token for `/load` (and other state-changing admin endpoints).\n\n[poc.zip](https://github.com/user-attachments/files/25079818/poc.zip)\n[PR_DESCRIPTION.md](https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md)",
  "published_at": "2026-02-24T20:37:35Z",
  "updated_at": "2026-02-27T19:54:36Z",
  "severity": "medium",
  "cvss_score": 4.0,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-879p-475x-rqh2",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2026-27589",
    "https://github.com/caddyserver/caddy/commit/65e0ddc22137bbbaa68c842ae0b98d0548504545",
    "https://github.com/caddyserver/caddy",
    "https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
    "https://github.com/user-attachments/files/25079818/poc.zip",
    "https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md",
    "https://pkg.go.dev/vuln/GO-2026-4537"
  ],
  "aliases": [
    "CVE-2026-27589",
    "GO-2026-4537",
    "GHSA-879p-475x-rqh2"
  ],
  "cve_ids": [
    "CVE-2026-27589"
  ],
  "ghsa_ids": [
    "GHSA-879p-475x-rqh2"
  ],
  "osv_ids": [
    "GHSA-879p-475x-rqh2",
    "GO-2026-4537"
  ],
  "affected_versions": [
    "introduced=0, fixed<2.11.1"
  ],
  "fixed_versions": [
    "2.11.1"
  ],
  "package_name": "github.com/caddyserver/caddy/v2",
  "render_markdown": false,
  "case_path": null,
  "secure_code_topics": [
    "proxy-trust-boundary",
    "request-smuggling-boundary",
    "token-cookie-storage",
    "plugin-extension-trust-policy",
    "dependency-upgrade-policy"
  ],
  "status": "generated",
  "triage_reasons": [],
  "entity_refs": [
    {
      "entity_id": "caddy",
      "entity_type": "system",
      "relation": "root-system",
      "root_system_id": "caddy",
      "official": true
    },
    {
      "entity_id": "caddy--repo--github-com-caddyserver-caddy-v2",
      "entity_type": "repo",
      "relation": "affected-component",
      "root_system_id": "caddy",
      "official": false
    }
  ],
  "affected_components": [
    {
      "name": "caddyserver / caddy / v2",
      "entity_id": "caddy--repo--github-com-caddyserver-caddy-v2",
      "scope": "repo",
      "package_name": "github.com/caddyserver/caddy/v2",
      "official": false
    }
  ],
  "affected_version_ranges": [
    "introduced=0, fixed<2.11.1"
  ],
  "fixed_version_ranges": [
    "2.11.1"
  ],
  "introduced_version": "introduced=0, fixed<2.11.1",
  "patched_version": "2.11.1",
  "version_evidence_sources": [
    "https://github.com/caddyserver/caddy/security/advisories/GHSA-879p-475x-rqh2",
    "https://nvd.nist.gov/vuln/detail/CVE-2026-27589",
    "https://github.com/caddyserver/caddy/commit/65e0ddc22137bbbaa68c842ae0b98d0548504545",
    "https://github.com/caddyserver/caddy",
    "https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
    "https://github.com/user-attachments/files/25079818/poc.zip",
    "https://github.com/user-attachments/files/25079820/PR_DESCRIPTION.md",
    "https://pkg.go.dev/vuln/GO-2026-4537"
  ],
  "affected_version_refs": [
    "caddy--repo--github-com-caddyserver-caddy-v2--introduced-0-fixed-2-11-1"
  ],
  "fixed_version_refs": [
    "caddy--repo--github-com-caddyserver-caddy-v2--2-11-1"
  ],
  "patched_version_refs": [
    "caddy--repo--github-com-caddyserver-caddy-v2--2-11-1"
  ],
  "version_sync_confidence": "high",
  "advisory_scope": "repo",
  "version_confidence": "high",
  "version_gap_reason": "",
  "version_resolution_needed": false,
  "workflow": {
    "workflow_id": "caddy--CVE-2026-27589--workflow",
    "vuln_family": "file-upload",
    "entry_surface": "upload-or-import-surface",
    "preconditions": [
      "\u4ec5\u5728 lab-local\u3001lab-public \u6216\u660e\u786e\u6388\u6743\u76ee\u6807\u4e2d\u6267\u884c\u3002",
      "\u786e\u8ba4\u76ee\u6807\u547d\u4e2d\u7248\u672c\u65ad\u8a00: introduced=0, fixed<2.11.1",
      "\u82e5\u5bf9\u8c61\u5c5e\u4e8e `repo`\uff0c\u5148\u786e\u8ba4\u6269\u5c55/\u4ed3\u5e93/\u5305\u5df2\u542f\u7528\u5e76\u5904\u4e8e\u53d7\u5f71\u54cd\u7248\u672c\u3002"
    ],
    "required_role": "authenticated-uploader",
    "affected_version_assertion": [
      "introduced=0, fixed<2.11.1"
    ],
    "trigger_vector": "\u5bf9 `file-upload` \u5bb6\u65cf\u5165\u53e3\u6295\u9012\u6700\u5c0f\u5316\u3001\u53ef\u5ba1\u8ba1\u3001\u53ef\u56de\u6eda\u7684\u53d7\u63a7\u8f93\u5165\uff0c\u6bd4\u8f83\u4fee\u590d\u524d\u540e\u5dee\u5f02\u3002",
    "request_or_ui_path": [
      "/upload",
      "/import",
      "/plugin/install"
    ],
    "input_shape": "\u63d0\u4ea4\u53d7\u63a7\u975e\u6267\u884c\u6837\u672c\uff0c\u9a8c\u8bc1\u6269\u5c55\u540d\u3001MIME\u3001\u843d\u76d8\u4e0e\u6267\u884c\u6743\u9650\u3002",
    "expected_unsafe_behavior": "\u4e0a\u4f20\u6837\u672c\u88ab\u9519\u8bef\u63a5\u53d7\u3001\u53ef\u8bbf\u95ee\u6216\u4f4d\u4e8e\u53ef\u6267\u884c\u8def\u5f84\u3002",
    "server_evidence_points": [
      "\u5e94\u7528\u65e5\u5fd7\u4e2d\u7684\u547d\u4e2d\u8def\u5f84\u3001\u9274\u6743\u51b3\u7b56\u548c\u5f02\u5e38\u6808",
      "\u53cd\u5411\u4ee3\u7406\u6216\u8fb9\u754c\u5c42\u65e5\u5fd7\u4e2d\u7684\u8bf7\u6c42\u5934\u3001\u6765\u6e90 IP \u4e0e\u8def\u7531\u51b3\u7b56"
    ],
    "browser_evidence_points": [
      "\u57fa\u7ebf\u622a\u56fe\u4e0e\u653b\u51fb\u540e\u622a\u56fe\u7684 DOM/\u89c6\u89c9\u5dee\u5f02",
      "console\u3001network \u4e0e response metadata \u4e2d\u7684\u5f02\u5e38\u4fe1\u53f7"
    ],
    "db_or_fs_evidence_points": [
      "\u6570\u636e\u5e93\u4e2d\u65b0\u589e/\u8d8a\u6743\u8bfb\u53d6\u7684\u6d4b\u8bd5\u6570\u636e",
      "\u6587\u4ef6\u7cfb\u7edf\u4e2d\u65b0\u589e\u4e0a\u4f20\u6837\u672c\u3001\u7f13\u5b58\u6761\u76ee\u6216\u8d8a\u6743\u8bfb\u53d6\u75d5\u8ff9"
    ],
    "detection_signals": [
      "WAF / reverse proxy \u5f02\u5e38\u65e5\u5fd7\u3001\u8bbf\u95ee\u65e5\u5fd7\u548c\u544a\u8b66",
      "\u5e94\u7528\u5ba1\u8ba1\u65e5\u5fd7\u4e2d\u7684\u6743\u9650\u9519\u8bef\u3001\u91cd\u5b9a\u5411\u5f02\u5e38\u3001\u6a21\u677f\u6e32\u67d3\u6216\u4e0a\u4f20\u843d\u76d8\u4e8b\u4ef6"
    ],
    "mitigation_summary": "\u4f18\u5148\u5347\u7ea7\u5230\u4fee\u590d\u7248\u672c\uff0c\u5e76\u540c\u65f6\u6536\u7d27\u8f93\u5165\u6821\u9a8c\u3001\u670d\u52a1\u7aef\u9274\u6743\u3001\u4ee3\u7406\u4fe1\u4efb\u8fb9\u754c\u3001\u6269\u5c55\u5b89\u88c5\u4fe1\u4efb\u548c\u5ba1\u8ba1\u65e5\u5fd7\u3002",
    "patch_validation_steps": [
      "\u786e\u8ba4\u76ee\u6807\u7248\u672c\u4ece `introduced=0, fixed<2.11.1` \u5347\u7ea7\u6216\u56de\u79fb\u5230 `2.11.1`\u3002",
      "\u4fdd\u7559\u540c\u4e00\u7ec4\u53d7\u63a7\u8f93\u5165\uff0c\u5728\u4fee\u590d\u524d\u540e\u5206\u522b\u6267\u884c\u5e76\u6bd4\u5bf9\u54cd\u5e94\u3001\u65e5\u5fd7\u4e0e\u6d4f\u89c8\u5668\u8bc1\u636e\u3002",
      "\u786e\u8ba4\u4fee\u590d\u540e\u4ec5\u4fdd\u7559\u9884\u671f\u4e1a\u52a1\u884c\u4e3a\uff0c\u4e0d\u518d\u89e6\u53d1\u8d8a\u6743\u3001\u56de\u663e\u3001\u5f02\u5e38\u6e32\u67d3\u6216\u9519\u8bef\u8bf7\u6c42\u3002",
      "\u8865\u5145 `file-upload` \u65cf\u81ea\u52a8\u5316\u56de\u5f52\uff0c\u907f\u514d\u540c\u7c7b\u8def\u5f84\u5728\u63d2\u4ef6\u3001\u4e3b\u9898\u6216\u4ee3\u7406\u94fe\u4e2d\u56de\u5f52\u3002"
    ],
    "lab_safety_notes": [
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      "\u7981\u6b62\u9020\u6210\u6301\u4e45\u7834\u574f\u3001\u8d8a\u6743\u4e0b\u8f7d\u771f\u5b9e\u6570\u636e\u6216\u4e0d\u53ef\u56de\u6eda side effect\u3002",
      "\u5982\u9700\u6d4f\u89c8\u5668\u8bc1\u636e\uff0c\u4fdd\u7559 baseline / proof \u4e24\u4efd\u5feb\u7167\u4ee5\u53ca console / network \u8bb0\u5f55\u3002"
    ],
    "review_state": "ready"
  },
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
  "last_verified_at": null,
  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
    "required": false,
    "present": false,
    "refs": []
  },
  "repro_profile_id": "file-upload-generic",
  "artifact_mode": "synthetic",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Caddy"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 2,
    "entity_ref_count": 2,
    "advisory_scope": "repo",
    "version_confidence": "high",
    "workflow_id": "caddy--CVE-2026-27589--workflow"
  }
}