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🛡️ Sentinel: [HIGH] Fix path traversal in manual TS module path resolution #161

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🛡️ Sentinel: [HIGH] Fix path traversal in manual TS module path resolution #161

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4 changes: 4 additions & 0 deletions .jules/sentinel.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
## 2025-05-15 - [Path Traversal in Manual Path Normalization]
**Vulnerability:** Manual path resolution using `components.pop()` on `std::path::Component::ParentDir` allowed path traversal. If a path like `../../a` was parsed, `components.pop()` on an empty `Vec` did nothing, turning the path into `a` instead of preserving the parent traversal. It could also pop `RootDir` or `Prefix` components, changing absolute paths to relative ones or traversing beyond intended roots.
**Learning:** `std::path::Component` normalization must handle empty lists and consecutive `ParentDir` components by pushing them instead of ignoring them. It must also explicitly avoid popping `RootDir` or `Prefix` components to prevent escaping virtual file systems or simulated root directories.
**Prevention:** Explicitly check if the `components` list is empty, if the last component is `ParentDir`, or if the last component is `RootDir` / `Prefix` before calling `pop()`.
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Copilot AI Apr 19, 2026

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New markdown files in this repo typically include an SPDX header (often via an HTML comment block) or are covered by a REUSE.toml annotation. This file currently has no SPDX metadata and appears not to be covered by the existing REUSE.toml annotations, which can cause the fsfe/reuse-action CI job to fail. Add an SPDX header to this file or extend REUSE.toml to cover .jules/**.

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13 changes: 12 additions & 1 deletion crates/flow/src/incremental/extractors/typescript.rs
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Expand Up @@ -808,7 +808,18 @@ impl TypeScriptDependencyExtractor {
for component in resolved.components() {
match component {
std::path::Component::ParentDir => {
components.pop();
let is_empty = components.is_empty();
let last_is_parent = matches!(components.last(), Some(std::path::Component::ParentDir));
let last_is_root_or_prefix = matches!(
components.last(),
Some(std::path::Component::RootDir) | Some(std::path::Component::Prefix(_))
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Copilot AI Apr 19, 2026

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components.last() returns Option<&std::path::Component>, but the matches! patterns here are written as if they were matching Option<std::path::Component>. This is likely a compile error (and will also be caught by clippy). Update the patterns to match references (e.g., Some(&Component::ParentDir) / Some(&Component::RootDir) / Some(&Component::Prefix(_))) or bind components.last() to a variable and match on *last/last appropriately.

Suggested change
let last_is_parent = matches!(components.last(), Some(std::path::Component::ParentDir));
let last_is_root_or_prefix = matches!(
components.last(),
Some(std::path::Component::RootDir) | Some(std::path::Component::Prefix(_))
let last_is_parent =
matches!(components.last(), Some(&std::path::Component::ParentDir));
let last_is_root_or_prefix = matches!(
components.last(),
Some(&std::path::Component::RootDir)
| Some(&std::path::Component::Prefix(_))

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);

if is_empty || last_is_parent {
components.push(component);
} else if !last_is_root_or_prefix {
components.pop();
}
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Copilot AI Apr 19, 2026

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This change fixes tricky .. normalization edge cases, but there are no tests covering the newly handled scenarios (leading ../../... that should remain relative, and .. following RootDir/Prefix that must not pop them). Please add unit tests exercising these cases so the security fix can’t regress silently; the existing resolve_module_path tests in crates/flow/tests/extractor_typescript_tests.rs can be extended with a couple of dedicated cases.

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}
std::path::Component::CurDir => {}
_ => components.push(component),
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