CVE-2026-71493: Infracost Arbitrary File Read Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-mmg6-4qmv-6pc8",
  "modified" : "2026-09-08T18:14:00Z",
  "published" : "2026-09-08T18:14:00Z",
  "aliases" : [ "CVE-2026-71493" ],
  "summary" : "Infracost: Arbitrary file read via config-template readFile symlink traversal",
  "details" : "### Impact\n\nPath traversal via link following in the Infracost config-template parser. The `readFile`, `pathExists`, `isDir`, and `matchPaths` template functions confined repo-supplied paths with a lexical `filepath.Rel` check plus a leaf-only `os.Lstat`:\n\n```\n{{ readFile \"evil/file\" }}\n```\n\nWith an intermediate directory symlink committed in the repo (`evil -> /`), the path is lexically clean and the leaf is a regular file, so both checks pass, but `os.ReadFile` follows the symlink and reads outside the checkout. The contents are rendered into the generated config and surfaced via the Infracost dashboard and PR comment, so anyone who can open a pull request can read files off the runner.\n\nAffects `infracost` up to and including `v0.10.44`. Successful exploitation reads any file the CLI process can reach on the runner. Impact depends on what the run exposes: under `on: pull_request` (the configuration in Infracost's documentation) fork pull requests run without secrets and with a read-only token, so exposure is limited. If Infracost runs under `pull_request_target`, or is triggered by a same-repository pull request, the read reaches the repository's secrets, enabling secret theft. The patch confines all four functions regardless of trigger.\n\n### Patches\n\nFixed in `v0.10.45` ([#3586](https://github.com/infracost/infracost/pull/3586)) by routing all four functions through `security.IsPathAllowed`, which resolves symlinks anywhere in the path before a segment-aware containment check. The same fix landed in [config#14](https://github.com/infracost/config/pull/14) and [parser#144](https://github.com/infracost/parser/pull/144).\n  - Installed via the official script, a package manager, or the `latest` Docker tag: upgrade to `v0.10.45` (or later) to receive the fix.\n  - Pinned to a specific version or image digest: bump to `v0.10.45`.\n\n### Workarounds\n\nNo full fix without upgrading. To limit exposure: run Infracost under `on: pull_request` rather than `pull_request_target`, and keep fork pull requests from receiving secrets (the defaults).",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/infracost/infracost"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.10.45"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/infracost/infracost/security/advisories/GHSA-mmg6-4qmv-6pc8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-71493"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/infracost/infracost/pull/3586"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/infracost/infracost/commit/4d39331afc0e27752d16d9d91c34583e5e8487fb"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/infracost/infracost"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/infracost/infracost/releases/tag/v0.10.45"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22", "CWE-59" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-08T18:14:00Z",
    "nvd_published_at" : "2026-08-21T18:16:50Z"
  }
}