{
  "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": [],
  "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
  }
}