🛡️ Sentinel: [CRITICAL] Fix path traversal in TypeScript module resolution

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2025-06-01 - Path Traversal Vulnerability in TypeScript Import Resolution
+**Vulnerability:** A path traversal vulnerability existed in the manual path normalization logic (`resolved.components()`) inside the TypeScript extractor's `resolve_import_path` when `canonicalize` fails. The code un-conditionally popped the last path component when encountering `std::path::Component::ParentDir`, which could erroneously pop `RootDir` (`/`) or `Prefix` (`C:\`), or incorrectly remove a legitimate preceding `../` in paths like `../../a`.
+**Learning:** This occurred because developers often assume `.pop()` on a vector of path components is safe for `..` without considering absolute roots, Windows prefixes, or multiple consecutive `..` components that should be preserved.
+**Prevention:** Explicitly match against the last component before popping. Block `Component::ParentDir` from popping `Component::RootDir` or `Component::Prefix`, and instead push `Component::ParentDir` if the components list is empty or its last element is also `Component::ParentDir`.

crates/ast-engine/src/tree_sitter/mod.rs

@@ -553,9 +553,8 @@ impl ContentExt for String {
         let mut bytes = std::mem::take(self).into_bytes();
         let original_len = bytes.len();
         bytes.splice(safe_start..safe_end, full_inserted);
-        *self = Self::from_utf8(bytes).unwrap_or_else(|e| {
-            Self::from_utf8_lossy(&e.into_bytes()).into_owned()
-        });
+        *self = Self::from_utf8(bytes)
+            .unwrap_or_else(|e| Self::from_utf8_lossy(&e.into_bytes()).into_owned());
 
         // We calculate new_end_byte using the difference in the new overall string length
         // to correctly align the end offset, taking any potential replacement bytes from
@@ -791,7 +790,10 @@ mod test {
 
         let tree2 = parse_lang(|p| p.parse(&src, Some(&tree)), &Tsx.get_ts_language())?;
         let fresh_tree = parse(&src)?;
-        assert_eq!(tree2.root_node().to_sexp(), fresh_tree.root_node().to_sexp());
+        assert_eq!(
+            tree2.root_node().to_sexp(),
+            fresh_tree.root_node().to_sexp()
+        );
         Ok(())
     }
 }

crates/flow/src/incremental/extractors/typescript.rs

@@ -808,7 +808,23 @@ impl TypeScriptDependencyExtractor {
                 for component in resolved.components() {
                     match component {
                         std::path::Component::ParentDir => {
-                            components.pop();
+                            // 🛡️ SECURITY: Prevent path traversal by explicitly blocking Component::ParentDir
+                            // from popping RootDir/Prefix. Also correctly handle when the component list
+                            // is empty or already ends with ParentDir to preserve paths like ../../a
+                            if let Some(last) = components.last() {
+                                match last {
+                                    std::path::Component::Normal(_) => {
+                                        components.pop();
+                                    }
+                                    std::path::Component::ParentDir => {
+                                        components.push(component);
+                                    }
+                                    // Don't pop RootDir or Prefix
+                                    _ => {}
+                                }
+                            } else {
+                                components.push(component);
+                            }
                         }
                         std::path::Component::CurDir => {}
                         _ => components.push(component),

crates/rule-engine/src/rule/mod.rs

@@ -246,7 +246,11 @@ impl Rule {
 
     pub fn defined_vars(&self) -> RapidSet<String> {
         match self {
-            Rule::Pattern(p) => p.defined_vars().into_iter().map(|s| s.to_string()).collect(),
+            Rule::Pattern(p) => p
+                .defined_vars()
+                .into_iter()
+                .map(|s| s.to_string())
+                .collect(),
             Rule::Kind(_) => RapidSet::default(),
             Rule::Regex(_) => RapidSet::default(),
             Rule::NthChild(n) => n.defined_vars(),

crates/rule-engine/src/rule/referent_rule.rs

@@ -27,10 +27,7 @@ impl<R> Clone for Registration<R> {
 
 impl<R> Registration<R> {
     fn read(&self) -> Arc<RapidMap<String, R>> {
-        self.0
-            .read()
-            .unwrap_or_else(|e| e.into_inner())
-            .clone()
+        self.0.read().unwrap_or_else(|e| e.into_inner()).clone()
     }
     pub(crate) fn contains_key(&self, key: &str) -> bool {
         self.read().contains_key(key)