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Fencer Vulns
low 3.3

GHSA-h4fr-cmh5-qr62 json

Fallow: A `.*` glob segment let an analyzed repository make Fallow test paths in the parent of the project root

published 2026-10-23 16 d ago modified 2026-10-23 16 d ago

cvss
3.3
version 3.1, GitHub
cisa kev
Not listed
not in CISA's catalog
epss
—
no score, EPSS covers CVEs only
public exploits
0
none known

Summary

### 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.

Patch / fix

  • npm fallow 3.34.0
  • npm @fallow-cli/fallow-node 3.34.0
  • crates.io fallow-cli 3.34.0
  • crates.io fallow-config 3.34.0
  • crates.io fallow-core 3.34.0

CVSS scores

assigned by version score vector
GitHub 3.1 3.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm fallow
<3.34.0
3.34.0
npm @fallow-cli/fallow-node
<3.34.0
3.34.0
crates.io fallow-cli
<3.34.0
3.34.0
crates.io fallow-config
<3.34.0
3.34.0
crates.io fallow-core
<3.34.0
3.34.0

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.