{
  "canonical_id": "fastify--CVE-2026-3419",
  "system_id": "fastify",
  "display_name": "Fastify",
  "category": "frameworks",
  "advisory_mode": "core",
  "title": "Fastify's Missing End Anchor in \"subtypeNameReg\" Allows Malformed Content-Types to Pass Validation",
  "summary": "# Description\n\nFastify incorrectly accepts malformed `Content-Type` headers containing trailing characters after the subtype token, in violation of [RFC 9110 \u00a78.3.1](https://httpwg.org/specs/rfc9110.html#field.content-type). For example, a request sent with `Content-Type: application/json garbage` passes validation and is processed normally, rather than being rejected with `415 Unsupported Media Type`.\n\nWhen regex-based content-type parsers are in use (a documented Fastify feature), the malformed value is matched against registered parsers using the full string including the trailing garbage. This means a request with an invalid content-type may be routed to and processed by a parser it should never have reached.\n\n## Impact\n\nAn attacker can send requests with RFC-invalid `Content-Type` headers that bypass validity checks, reach content-type parser matching, and be processed by the server. Requests that should be rejected at the validation stage are instead handled as if the content-type were valid.\n\n## Workarounds\n\nDeploy a WAF rule to protect against this\n\n## Fix\n\nThe fix is available starting with v5.8.1.",
  "published_at": "2026-03-05T21:29:54Z",
  "updated_at": "2026-03-16T03:05:26.332715Z",
  "severity": "low",
  "cvss_score": 3.1,
  "exploit_status": "unknown",
  "source_confidence": "official",
  "official_source_url": "https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9",
  "secondary_source_urls": [
    "https://nvd.nist.gov/vuln/detail/CVE-2026-3419",
    "https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7",
    "https://cna.openjsf.org/security-advisories.html",
    "https://github.com/advisories/GHSA-573f-x89g-hqp9",
    "https://github.com/fastify/fastify",
    "https://httpwg.org/specs/rfc9110.html#field.content-type",
    "https://www.cve.org/CVERecord?id=CVE-2026-3419"
  ],
  "aliases": [
    "CVE-2026-3419",
    "GHSA-573f-x89g-hqp9"
  ],
  "cve_ids": [
    "CVE-2026-3419"
  ],
  "ghsa_ids": [
    "GHSA-573f-x89g-hqp9"
  ],
  "osv_ids": [
    "GHSA-573f-x89g-hqp9"
  ],
  "affected_versions": [
    "introduced=5.7.2, fixed<5.8.1"
  ],
  "fixed_versions": [
    "5.8.1"
  ],
  "package_name": "fastify",
  "render_markdown": true,
  "case_path": "07-framework-security/frameworks/fastify/cases/fastify-cve-2026-3419.md",
  "secure_code_topics": [
    "proxy-trust-boundary",
    "ssrf-url-validation",
    "xss-output-encoding",
    "token-cookie-storage"
  ],
  "status": "generated",
  "triage_reasons": [],
  "entity_refs": [
    {
      "entity_id": "fastify",
      "entity_type": "system",
      "relation": "root-system",
      "root_system_id": "fastify",
      "official": true
    },
    {
      "entity_id": "fastify--project--fastify",
      "entity_type": "project",
      "relation": "affected-component",
      "root_system_id": "fastify",
      "official": false
    }
  ],
  "affected_components": [
    {
      "name": "fastify",
      "entity_id": "fastify--project--fastify",
      "scope": "package",
      "package_name": "fastify",
      "official": false
    }
  ],
  "affected_version_ranges": [
    "introduced=5.7.2, fixed<5.8.1"
  ],
  "fixed_version_ranges": [
    "5.8.1"
  ],
  "introduced_version": "introduced=5.7.2, fixed<5.8.1",
  "patched_version": "5.8.1",
  "version_evidence_sources": [
    "https://github.com/fastify/fastify/security/advisories/GHSA-573f-x89g-hqp9",
    "https://nvd.nist.gov/vuln/detail/CVE-2026-3419",
    "https://github.com/fastify/fastify/commit/67f6c9b32cb3623d3c9470cc17ed830dd2f083d7",
    "https://cna.openjsf.org/security-advisories.html",
    "https://github.com/advisories/GHSA-573f-x89g-hqp9",
    "https://github.com/fastify/fastify",
    "https://httpwg.org/specs/rfc9110.html#field.content-type",
    "https://www.cve.org/CVERecord?id=CVE-2026-3419"
  ],
  "advisory_scope": "package",
  "version_confidence": "high",
  "version_gap_reason": "",
  "version_resolution_needed": false,
  "workflow": {
    "workflow_id": "fastify--CVE-2026-3419--workflow",
    "vuln_family": "xss",
    "entry_surface": "web-ui-render-path",
    "preconditions": [
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    "required_role": "editor-or-admin",
    "affected_version_assertion": [
      "introduced=5.7.2, fixed<5.8.1"
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    "trigger_vector": "\u5bf9 `xss` \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": [
      "/admin/editor",
      "/preview",
      "/rendered-content"
    ],
    "input_shape": "\u53d7\u63a7 HTML/Markdown/\u5bcc\u6587\u672c\u8f93\u5165\uff0c\u89c2\u5bdf\u6e32\u67d3\u4e0a\u4e0b\u6587\u662f\u5426\u5931\u53bb\u7f16\u7801\u6216\u51c0\u5316\u3002",
    "expected_unsafe_behavior": "\u8f93\u5165\u5728\u76ee\u6807\u4e0a\u4e0b\u6587\u6267\u884c\u6216\u88ab\u6d4f\u89c8\u5668\u89e3\u91ca\u4e3a\u4e3b\u52a8\u5185\u5bb9\u3002",
    "server_evidence_points": [
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      "\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": [
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    ],
    "detection_signals": [
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      "\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"
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    "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": [
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    ],
    "lab_safety_notes": [
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    ],
    "review_state": "ready"
  },
  "verification_status": "triage-manual",
  "verification_mode": "synthetic",
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  "last_run_id": null,
  "evidence_bundle": null,
  "historical_status": null,
  "latest_status": null,
  "browser_evidence": {
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    "present": false,
    "refs": []
  },
  "repro_profile_id": "xss-generic",
  "artifact_mode": "synthetic",
  "blocked_reason": null,
  "metadata": {
    "source_names": [
      "OSV Fastify"
    ],
    "source_kinds": [
      "osv-batch"
    ],
    "candidate_count": 1,
    "entity_ref_count": 2,
    "advisory_scope": "package",
    "version_confidence": "high",
    "workflow_id": "fastify--CVE-2026-3419--workflow"
  }
}