GHSA-2jq4-q6vv-4cp3: Crawl4AI Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-2jq4-q6vv-4cp3",
  "modified" : "2026-06-18T17:25:13Z",
  "published" : "2026-06-18T17:25:13Z",
  "aliases" : [ ],
  "summary" : "Crawl4AI: Arbitrary file write (path traversal) in crawler downloads can lead to RCE",
  "details" : "### Summary\n\nWhen the crawler saves a downloaded file, the destination filename was taken from attacker-influenced input and joined to the downloads directory with no confinement. A filename containing an absolute path (e.g. `/etc/cron.d/evil`) or `../` traversal escaped the downloads directory, giving an arbitrary file write with attacker-controlled contents. Because the written bytes are attacker-controlled, this escalates to remote code execution (overwriting a shell rc-file, `~/.ssh/authorized_keys`, a cron entry, or a Python module on the import path).\n\n### Affected paths\n\nTwo download sinks in `crawl4ai/async_crawler_strategy.py`:\n- HTTP crawler (`AsyncHTTPCrawlerStrategy`): the filename is parsed from the response `Content-Disposition` header by `_extract_filename()` and written via `aiofiles.open(filepath, 'wb')`. Reachable directly via the SDK, and via the unauthenticated Docker `/crawl` endpoint when an `HTTPCrawlerConfig` is supplied.\n- Browser crawler (`AsyncPlaywrightCrawlerStrategy`): the download's `suggested_filename` (controllable by the visited page) is joined to `downloads_path` and written via `download.save_as()`.\n\nThe HTTP-strategy sink is reachable pre-auth on the default Docker deployment; both are reachable for SDK users simply by crawling an attacker-controlled URL. The default Playwright crawl path that does not trigger a download is unaffected.\n\n### Impact\n\nArbitrary file write with attacker-controlled content as the user running the crawler, escalating to remote code execution.\n\n### Fix\n\nBoth sinks now resolve the destination through a single hardened helper (`_safe_download_filepath`) that reduces the attacker-influenced name to a bare basename (dropping absolute paths and `..` components) and re-checks, via `realpath`, that the resolved path stays inside the downloads root (defeating symlink/TOCTOU escapes). A traversal attempt is rejected; normal downloads are unchanged.\n\n### Workarounds\n\n- Upgrade to the patched version (0.9.0).\n- Run the crawler as an unprivileged user with a dedicated, isolated downloads directory on a volume with no sensitive paths writable.\n- Enable authentication (`CRAWL4AI_API_TOKEN`) on the Docker server.\n\n### Credits\n\nY4tacker - reported the Content-Disposition path traversal in the HTTP crawler with a clear PoC and a basename + realpath-containment fix recommendation.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "crawl4ai"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.9.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.9"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/unclecode/crawl4ai/security/advisories/GHSA-2jq4-q6vv-4cp3"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/unclecode/crawl4ai"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22", "CWE-59" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T17:25:13Z",
    "nvd_published_at" : null
  }
}