GitHub Advisoryadvisory · npm, crates.io
GHSA-h4fr-cmh5-qr62 Fallow: A `.*` glob segment let an analyzed repository make Fallow test paths in the parent of the project root
LOW
Official page ↗
- Ecosystem
- npm, crates.io
- Packages
- fallow, @fallow-cli/fallow-node, fallow-cli, fallow-config, fallow-core
- Severity
- Low
- CVSS vector
- CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- Weaknesses
- CWE-22
- Reviewed
- 2026-10-23
Affected packages
• npm fallow: < 3.34.0 → fixed in 3.34.0
• npm @fallow-cli/fallow-node: < 3.34.0 → fixed in 3.34.0
• crates.io fallow-cli: < 3.34.0 → fixed in 3.34.0
• crates.io fallow-config: < 3.34.0 → fixed in 3.34.0
• crates.io fallow-core: < 3.34.0 → fixed in 3.34.0
Description
Impact
Fallow expands some globs from the analyzed repository on disk. Before 3.34.0, a segment such as `.*`, `.?` or `..*` in such a glob also matched the special `..` entry. The `glob` crate tests `..` against a segment that starts with a literal `.`. Fallow validates plugin glob patterns and refuses absolute paths and `..` segments, but these segments passed that validation.
The attacker controls the repository content. The attacker must also be able to read the Fallow output, for example a CI log or a pull request comment. Then the attacker can learn if a file or directory exists in the parent of the project root:
• A plugin `fileExists` detection pattern such as `.*/marker.json` made the plugin active when `marker.json` existed in the parent directory.
• An external plugin `configPatterns` or `alwaysUsed` pattern could match a config file in the parent directory. When the plugin was active and declared `toolingDependencies`, the tooling detection credited the related dev dependency. An unused dependency finding could then disappear, and `--trace-dependency` printed the outside path.
• `fallow plugin-check` reported `path_exists: true` for a seeded entry that matched only in the parent directory.
Fallow tested only that these paths exist. It did not read or print the content of a file outside the project root through these globs.
The Jest, Vitest and Rstest project globs had the same `.*` problem, and the Jest and Vitest ones also read file content. GHSA-jfwm-3p3c-6hx5 describes that case.
Patches
Fixed in 3.34.0. Fallow now rewrites a leading `.` in a wildcard segment to `[.]` before it expands the glob on disk. `[.]` matches the same hidden files and directories inside the project root. The `glob` crate does not test `..` against it.
Workarounds
Run Fallow only on repositories that you trust. Before you run Fallow on another repository, check the `detection`, `configPatterns` and `alwaysUsed` patterns of its plugin files.
Related
Weakness · CWE (1)
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory weakness
References
- https://github.com/fallow-rs/fallow/security/advisories/GHSA-h4fr-cmh5-qr62 web
- https://github.com/fallow-rs/fallow/pull/3548 web
- https://github.com/fallow-rs/fallow/commit/133d4c862c74f4b1f0a7417c65b7157c1144294d web
- https://github.com/fallow-rs/fallow package
- https://github.com/fallow-rs/fallow/releases/tag/v3.34.0 web