181 行
12 KiB
JSON
181 行
12 KiB
JSON
{
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"canonical_id": "caddy--CVE-2026-27586",
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"system_id": "caddy",
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"display_name": "Caddy",
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"category": "servers",
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"advisory_mode": "server",
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"title": "Caddy: mTLS client authentication silently fails open when CA certificate file is missing or malformed",
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"summary": "### Summary\n\nTwo swallowed errors in `ClientAuthentication.provision()` cause mTLS client certificate authentication to silently fail open when a CA certificate file is missing, unreadable, or malformed. The server starts without error but accepts any client certificate signed by any system-trusted CA, completely bypassing the intended private CA trust boundary.\n\n### Details\n\nIn `modules/caddytls/connpolicy.go`, the `provision()` method has two `return nil` statements that should be `return err`:\n\n**Bug #1 \u2014 line 787:**\n```go\nders, err := convertPEMFilesToDER(fpath)\nif err != nil {\n return nil // BUG: should be \"return err\"\n}\n```\n\n**Bug #2 \u2014 line 800:**\n```go\nerr := caPool.Provision(ctx)\nif err != nil {\n return nil // BUG: should be \"return err\"\n}\n```\n\nCompare with line 811 which correctly returns the error:\n```go\ncaRaw, err := ctx.LoadModule(clientauth, \"CARaw\")\nif err != nil {\n return err // CORRECT\n}\n```\n\nWhen the error is swallowed on line 787, the chain is:\n\n1. `TrustedCACerts` remains empty (no DER data appended from the file)\n2. The `len(clientauth.TrustedCACerts) > 0` guard on line 794 is false \u2014 skipped\n3. `clientauth.CARaw` is nil \u2014 line 806 returns nil\n4. `clientauth.ca` remains nil \u2014 no CA pool was created\n5. `provision()` returns nil \u2014 caller thinks provisioning succeeded\n\nThen in `ConfigureTLSConfig()`:\n\n6. `Active()` returns true because `TrustedCACertPEMFiles` is non-empty\n7. Default mode is set to `RequireAndVerifyClientCert` (line 860)\n8. But `clientauth.ca` is nil, so `cfg.ClientCAs` is never set (line 867 skipped)\n9. Go's `crypto/tls` with `RequireAndVerifyClientCert` + nil `ClientCAs` verifies client certs against the **system root pool** instead of the intended CA\n\nThe fix is changing `return nil` to `return err` on lines 787 and 800.\n\n### PoC\n\n1. Configure Caddy with mTLS pointing to a nonexistent CA file:\n\n```\n{\n \"apps\": {\n \"http\": {\n \"servers\": {\n \"srv0\": {\n \"listen\": [\":443\"],\n \"tls_connection_policies\": [{\n \"client_authentication\": {\n \"trusted_ca_certs_pem_files\": [\"/nonexistent/ca.pem\"]\n }\n }]\n }\n }\n }\n }\n}\n```\n\n2. Start Caddy \u2014 it starts without any error or warning.\n\n3. Connect with any client certificate (even self-signed):\n```bash\nopenssl s_client -connect localhost:443 -cert client.pem -key client-key.pem\n```\n\n4. The TLS handshake succeeds despite the certificate not being signed by the intended CA.\n\nA full Go test that proves the bug end-to-end (including a successful TLS handshake with a random self-signed client cert) is here: https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48\n\nTest output:\n```\n=== RUN TestSwallowedErrorMTLSFailOpen\n BUG CONFIRMED: provision() swallowed the error from a nonexistent CA file.\n tls.Config has RequireAndVerifyClientCert but ClientCAs is nil.\n CRITICAL: TLS handshake succeeded with a self-signed client cert!\n The server accepted a client certificate NOT signed by the intended CA.\n--- PASS: TestSwallowedErrorMTLSFailOpen (0.03s)\n```\n\n### Impact\n\nAny deployment using `trusted_ca_cert_file` or `trusted_ca_certs_pem_files` for mTLS will silently degrade to accepting any system-trusted client certificate if the CA file becomes unavailable. This can happen due to a typo in the path, file rotation, corruption, or permission changes. The server gives no indication that mTLS is misconfigured.",
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"published_at": "2026-02-24T20:22:53Z",
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"updated_at": "2026-02-27T19:52:41Z",
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"severity": "medium",
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"cvss_score": 4.0,
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"exploit_status": "unknown",
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"source_confidence": "official",
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"official_source_url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7",
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"secondary_source_urls": [
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"https://nvd.nist.gov/vuln/detail/CVE-2026-27586",
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"https://github.com/caddyserver/caddy/commit/d42d39b4bc237c628f9a95363b28044cb7a7fe72",
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"https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48",
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"https://github.com/caddyserver/caddy",
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"https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
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"https://pkg.go.dev/vuln/GO-2026-4539"
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],
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"aliases": [
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"CVE-2026-27586",
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"GO-2026-4539",
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"GHSA-hffm-g8v7-wrv7"
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],
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"cve_ids": [
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"CVE-2026-27586"
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],
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"ghsa_ids": [
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"GHSA-hffm-g8v7-wrv7"
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],
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"osv_ids": [
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"GHSA-hffm-g8v7-wrv7",
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"GO-2026-4539"
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],
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"affected_versions": [
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"introduced=0, fixed<2.11.1"
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],
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"fixed_versions": [
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"2.11.1"
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],
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"package_name": "github.com/caddyserver/caddy/v2",
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"render_markdown": false,
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"case_path": null,
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"secure_code_topics": [
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"proxy-trust-boundary",
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"request-smuggling-boundary",
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"plugin-extension-trust-policy"
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],
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"status": "generated",
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"triage_reasons": [],
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"entity_refs": [
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{
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"entity_id": "caddy",
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"entity_type": "system",
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"relation": "root-system",
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"root_system_id": "caddy",
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"official": true
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},
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{
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"entity_id": "caddy--repo--github-com-caddyserver-caddy-v2",
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"entity_type": "repo",
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"relation": "affected-component",
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"root_system_id": "caddy",
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"official": false
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}
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],
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"affected_components": [
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{
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"name": "caddyserver / caddy / v2",
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"entity_id": "caddy--repo--github-com-caddyserver-caddy-v2",
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"scope": "repo",
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"package_name": "github.com/caddyserver/caddy/v2",
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"official": false
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}
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],
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"affected_version_ranges": [
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"introduced=0, fixed<2.11.1"
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],
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"fixed_version_ranges": [
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"2.11.1"
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],
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"introduced_version": "introduced=0, fixed<2.11.1",
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"patched_version": "2.11.1",
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"version_evidence_sources": [
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"https://github.com/caddyserver/caddy/security/advisories/GHSA-hffm-g8v7-wrv7",
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"https://nvd.nist.gov/vuln/detail/CVE-2026-27586",
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"https://github.com/caddyserver/caddy/commit/d42d39b4bc237c628f9a95363b28044cb7a7fe72",
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"https://gist.github.com/moscowchill/9566c79c76c0b64c57f8bd0716f97c48",
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"https://github.com/caddyserver/caddy",
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"https://github.com/caddyserver/caddy/releases/tag/v2.11.1",
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"https://pkg.go.dev/vuln/GO-2026-4539"
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],
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"advisory_scope": "repo",
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"version_confidence": "high",
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"version_gap_reason": "",
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"version_resolution_needed": false,
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"workflow": {
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"workflow_id": "caddy--CVE-2026-27586--workflow",
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"vuln_family": "proxy-boundary",
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"entry_surface": "proxy-header-or-trust-boundary",
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"preconditions": [
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"\u4ec5\u5728 lab-local\u3001lab-public \u6216\u660e\u786e\u6388\u6743\u76ee\u6807\u4e2d\u6267\u884c\u3002",
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"\u786e\u8ba4\u76ee\u6807\u547d\u4e2d\u7248\u672c\u65ad\u8a00: introduced=0, fixed<2.11.1",
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"\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"
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],
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"required_role": "reverse-proxy-or-edge-client",
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"affected_version_assertion": [
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"introduced=0, fixed<2.11.1"
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],
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"trigger_vector": "\u5bf9 `proxy-boundary` \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",
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"request_or_ui_path": [
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"/middleware",
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"/x-forwarded-* trust path"
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],
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"input_shape": "\u63d0\u4ea4\u53d7\u63a7\u4ee3\u7406\u5934\u6216\u6765\u6e90\u5934\uff0c\u9a8c\u8bc1\u4fe1\u4efb\u8fb9\u754c\u548c\u56de\u6e90\u9274\u6743\u3002",
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"expected_unsafe_behavior": "\u4ec5\u51ed\u4ee3\u7406\u5934\u5373\u53ef\u8d8a\u8fc7\u9274\u6743\u6216\u6765\u6e90\u63a7\u5236\u3002",
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"server_evidence_points": [
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"\u5e94\u7528\u65e5\u5fd7\u4e2d\u7684\u547d\u4e2d\u8def\u5f84\u3001\u9274\u6743\u51b3\u7b56\u548c\u5f02\u5e38\u6808",
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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"
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],
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"browser_evidence_points": [
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"\u57fa\u7ebf\u622a\u56fe\u4e0e\u653b\u51fb\u540e\u622a\u56fe\u7684 DOM/\u89c6\u89c9\u5dee\u5f02",
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"console\u3001network \u4e0e response metadata \u4e2d\u7684\u5f02\u5e38\u4fe1\u53f7"
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],
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"db_or_fs_evidence_points": [
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"\u6570\u636e\u5e93\u4e2d\u65b0\u589e/\u8d8a\u6743\u8bfb\u53d6\u7684\u6d4b\u8bd5\u6570\u636e",
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"\u6587\u4ef6\u7cfb\u7edf\u4e2d\u65b0\u589e\u4e0a\u4f20\u6837\u672c\u3001\u7f13\u5b58\u6761\u76ee\u6216\u8d8a\u6743\u8bfb\u53d6\u75d5\u8ff9"
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],
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"detection_signals": [
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"WAF / reverse proxy \u5f02\u5e38\u65e5\u5fd7\u3001\u8bbf\u95ee\u65e5\u5fd7\u548c\u544a\u8b66",
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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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"\u4e0a\u6e38\u4ee3\u7406\u4e0e\u5e94\u7528\u5c42\u5bf9 Content-Length / Transfer-Encoding / forwarded headers \u7684\u89e3\u91ca\u5dee\u5f02"
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],
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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",
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"patch_validation_steps": [
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"\u786e\u8ba4\u76ee\u6807\u7248\u672c\u4ece `introduced=0, fixed<2.11.1` \u5347\u7ea7\u6216\u56de\u79fb\u5230 `2.11.1`\u3002",
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"\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",
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"\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",
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"\u8865\u5145 `proxy-boundary` \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"
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],
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"lab_safety_notes": [
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"\u53ea\u4f7f\u7528\u56de\u73af\u5730\u5740\u3001\u54e8\u5175\u76ee\u6807\u3001\u65e0\u5bb3\u6837\u672c\u6216\u53ef\u56de\u6eda\u6d4b\u8bd5\u6570\u636e\u3002",
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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",
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"\u5982\u9700\u6d4f\u89c8\u5668\u8bc1\u636e\uff0c\u4fdd\u7559 baseline / proof \u4e24\u4efd\u5feb\u7167\u4ee5\u53ca console / network \u8bb0\u5f55\u3002"
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],
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"review_state": "ready"
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},
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"verification_status": "triage-manual",
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"verification_mode": "synthetic",
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"last_verified_at": null,
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"last_run_id": null,
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"evidence_bundle": null,
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"historical_status": null,
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"latest_status": null,
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"browser_evidence": {
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"required": false,
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"present": false,
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"refs": []
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},
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"repro_profile_id": "authz-bypass-generic",
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"artifact_mode": "synthetic",
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"blocked_reason": null,
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"metadata": {
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"source_names": [
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"OSV Caddy"
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],
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"source_kinds": [
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"osv-batch"
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],
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"candidate_count": 2,
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"entity_ref_count": 2,
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"advisory_scope": "repo",
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"version_confidence": "high",
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"workflow_id": "caddy--CVE-2026-27586--workflow"
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}
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}
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