{"id":"GHSA-mmg6-4qmv-6pc8","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 -\u003e /`), 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).","aliases":["CVE-2026-71493","GO-2026-6439"],"modified":"2026-09-10T15:25:28.705709838Z","published":"2026-09-08T18:14:00Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-09-08T18:14:00Z","nvd_published_at":"2026-08-21T18:16:50Z","cwe_ids":["CWE-22","CWE-59"],"severity":"MODERATE"},"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"}],"affected":[{"package":{"name":"github.com/infracost/infracost","ecosystem":"Go","purl":"pkg:golang/github.com/infracost/infracost"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.10.45"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-mmg6-4qmv-6pc8/GHSA-mmg6-4qmv-6pc8.json"}}],"schema_version":"1.9.0","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"}]}