CVE-2026-44220: ciguard Discover_pipeline_files Follows Symlinks Out Of Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8cxw-cc62-q28v",
  "modified" : "2026-05-15T23:51:39Z",
  "published" : "2026-05-05T22:19:23Z",
  "aliases" : [ "CVE-2026-44220" ],
  "summary" : "ciguard: discover_pipeline_files follows symlinks out of scan root",
  "details" : "## Summary\n\nThe `discover_pipeline_files()` function in `src/ciguard/discovery.py` (introduced in v0.8.0 and used by the MCP `scan_repo` tool shipped in v0.8.1) walks a directory tree following symlinks, with cycle protection via tracking visited resolved paths. An attacker who can plant a symlink in a directory the user (or AI agent) scans can cause discovery to walk into the symlink target and return paths to pipeline-shaped files outside the requested root.\n\n## Threat scenario\n\n**MCP confused-deputy.** A user runs Claude Desktop / Claude Code / Cursor with the ciguard MCP server registered. The agent is fed an adversarial prompt to scan a directory containing planted symlinks (e.g. via a malicious clone or extracted tarball). `ciguard.scan_repo` walks the symlinks, returning paths and (via subsequent `scan` calls) file content from `~/.aws/`, `~/.config/`, `/etc/some-pipeline-config/`, etc. Pipeline files often contain hardcoded secrets, internal hostnames, deploy keys.\n\n## Patch\n\n- New `follow_symlinks: bool = False` parameter on `discover_pipeline_files`. Default refuses to descend into symlinked directories OR symlinked files.\n- Belt-and-braces: results are filtered to those whose `.resolve()` lies under `root.resolve()`, applied even when callers opt in to `follow_symlinks=True`.\n- 3 regression tests in `tests/test_discovery.py::TestSymlinkSafety`.\n\n## Discovery\n\nFound during ciguard's first self-conducted penetration test cycle (PTES + OWASP TG v4.2 + CREST framing), 2026-04-26.\n\n## CVSS Scoring\n\n- CVSS v3.1: `CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:N/A:N` — 4.4 (Medium)\n- CVSS v4.0: `CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N` — first.org calc 5.7 (Medium); GitHub's calc returns 2.4 (Low). Vector is correct — calculator profiles differ.\n\n## Reproduction\n\n```python\nfrom pathlib import Path\nfrom ciguard.discovery import discover_pipeline_files\n# In a victim dir, plant: trojan -> /etc\n# (or any other accessible dir containing pipeline-shaped files)\nfor f in discover_pipeline_files(Path('/tmp/victim')):\n    print(f)  # pre-fix: includes paths under /etc; post-fix: only /tmp/victim/\n```\n\n## References\n\n- Fix released in [v0.8.2](https://github.com/Jo-Jo98/ciguard/releases/tag/v0.8.2)\n- CI regression gate added in [v0.8.3](https://github.com/Jo-Jo98/ciguard/releases/tag/v0.8.3)\n- https://www.cve.org/CVERecord?id=CVE-2026-44220\n\nSee also: [GHSA-w828-4qhx-vxx3](https://github.com/advisories/GHSA-w828-4qhx-vxx3) — same conceptual pattern (path-validation flaw in an AI-agent tool) in Claude SDK for Python, CWE-59 + CWE-367",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "ciguard"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0.8.0"
      }, {
        "fixed" : "0.8.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.8.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Jo-Jo98/ciguard/security/advisories/GHSA-8cxw-cc62-q28v"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-44220"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Jo-Jo98/ciguard"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Jo-Jo98/ciguard/releases/tag/v0.8.2"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Jo-Jo98/ciguard/releases/tag/v0.8.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-59" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-05T22:19:23Z",
    "nvd_published_at" : "2026-05-12T20:16:42Z"
  }
}