Fallow glob lets repository content probe paths outside project root
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
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- Confidentiality · integrity · availability
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- Fix status
- Fixed
No CVSS vector from any source. Fix status from GitHub.
Summary
Fallow versions before 3.34.0 are affected, including the npm packages fallow and @fallow-cli/fallow-node and the crates fallow-cli, fallow-config and fallow-core. A glob segment such as .* also matches the parent directory entry .., which passes the validation that rejects parent directory segments (CWE-22). An attacker who controls repository content and can read Fallow output can learn whether a file or directory exists in the parent of the project root, but the flaw does not expose file contents.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
Description from the GitHub advisory
### 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.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | fallow (npm) | before 3.34.0 | 3.34.0 | Patch available | GHSA-h4fr-cmh5-qr62 |
| — | @fallow-cli/fallow-node (npm) | before 3.34.0 | 3.34.0 | Patch available | GHSA-h4fr-cmh5-qr62 |
| — | fallow-cli (crates.io) | before 3.34.0 | 3.34.0 | Patch available | GHSA-h4fr-cmh5-qr62 |
| — | fallow-config (crates.io) | before 3.34.0 | 3.34.0 | Patch available | GHSA-h4fr-cmh5-qr62 |
| — | fallow-core (crates.io) | before 3.34.0 | 3.34.0 | Patch available | GHSA-h4fr-cmh5-qr62 |
- fallow (npm) Vendor— Affected before 3.34.0 Fixed in 3.34.0 Patch available GHSA-h4fr-cmh5-qr62
- @fallow-cli/fallow-node (npm) Vendor— Affected before 3.34.0 Fixed in 3.34.0 Patch available GHSA-h4fr-cmh5-qr62
- fallow-cli (crates.io) Vendor— Affected before 3.34.0 Fixed in 3.34.0 Patch available GHSA-h4fr-cmh5-qr62
- fallow-config (crates.io) Vendor— Affected before 3.34.0 Fixed in 3.34.0 Patch available GHSA-h4fr-cmh5-qr62
- fallow-core (crates.io) Vendor— Affected before 3.34.0 Fixed in 3.34.0 Patch available GHSA-h4fr-cmh5-qr62
Remediation
Upgrade fallow, @fallow-cli/fallow-node, fallow-cli, fallow-config and fallow-core to 3.34.0. Until then, run Fallow only on repositories you trust and check the detection, configPatterns and alwaysUsed patterns of their plugin files before running it.
Written with Claude Haiku 5.5 from the sources below · 2026-10-28
- Fix · GHSA-h4fr-cmh5-qr62 fallow (npm) Fixed in 3.34.0 Advisory →
- Fix · GHSA-h4fr-cmh5-qr62 @fallow-cli/fallow-node (npm) Fixed in 3.34.0 Advisory →
- Fix · GHSA-h4fr-cmh5-qr62 fallow-cli (crates.io) Fixed in 3.34.0 Advisory →
- Fix · GHSA-h4fr-cmh5-qr62 fallow-config (crates.io) Fixed in 3.34.0 Advisory →
- Fix · GHSA-h4fr-cmh5-qr62 fallow-core (crates.io) Fixed in 3.34.0 Advisory →
Timeline
- 2026-10-23 Threatist record created from GHSA-h4fr-cmh5-qr62
References
Other 5
Sources
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