From 8a611c9be1d22c6066418aef8c1b5ffe90afcb9b Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Thu, 11 Jun 2026 18:03:34 +0000
Subject: [PATCH] =?UTF-8?q?=F0=9F=9B=A1=EF=B8=8F=20Sentinel:=20[HIGH]=20Fi?=
 =?UTF-8?q?x=20path=20traversal=20in=20manual=20path=20normalization?=
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Co-authored-by: bashandbone <89049923+bashandbone@users.noreply.github.com>
---
 .jules/sentinel.md                                  |  4 ++++
 .../flow/src/incremental/extractors/typescript.rs   | 13 ++++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 .jules/sentinel.md

diff --git a/.jules/sentinel.md b/.jules/sentinel.md
new file mode 100644
index 00000000..8cbbab43
--- /dev/null
+++ b/.jules/sentinel.md
@@ -0,0 +1,4 @@
+## 2024-06-11 - [Path Traversal] Improper Manual Path Normalization in TypeScript Extractor
+**Vulnerability:** A path traversal vulnerability existed in `crates/flow/src/incremental/extractors/typescript.rs` during manual module path resolution fallback. When resolving `../` components using `std::path::Component::ParentDir`, the code unconditionally popped the last component from the constructed path. This allowed `../` components to pop root directories (`Component::RootDir`), prefixes (`Component::Prefix`), or ignore leading `../` sequences, potentially leading to unauthorized path traversal and incorrect relative path construction.
+**Learning:** Manual path normalization is error-prone. In Rust's `std::path::Component` iteration, `Component::ParentDir` must be handled contextually. It should never pop root or prefix components, and if a path starts with `ParentDir` (or only contains `ParentDir`s so far), the `ParentDir` must be explicitly pushed onto the stack to preserve relative navigation, rather than ignored or attempting to pop an empty list.
+**Prevention:** When performing manual path component normalization, always match on the last pushed component type. Explicitly block `Component::ParentDir` from popping `RootDir` or `Prefix`, and ensure it is pushed when the list is empty or the last item is also a `ParentDir`.
diff --git a/crates/flow/src/incremental/extractors/typescript.rs b/crates/flow/src/incremental/extractors/typescript.rs
index 1bdda4ef..3f140692 100644
--- a/crates/flow/src/incremental/extractors/typescript.rs
+++ b/crates/flow/src/incremental/extractors/typescript.rs
@@ -808,7 +808,18 @@ impl TypeScriptDependencyExtractor {
                 for component in resolved.components() {
                     match component {
                         std::path::Component::ParentDir => {
-                            components.pop();
+                            if let Some(last) = components.last() {
+                                match last {
+                                    std::path::Component::ParentDir => components.push(component),
+                                    std::path::Component::Normal(_) => {
+                                        components.pop();
+                                    }
+                                    // Do not pop RootDir or Prefix
+                                    _ => {}
+                                }
+                            } else {
+                                components.push(component);
+                            }
                         }
                         std::path::Component::CurDir => {}
                         _ => components.push(component),