From 62fe413a523b06775fe93d410c68994f3002dcc7 Mon Sep 17 00:00:00 2001
From: Wyatt Alt <wyatt.alt@gmail.com>
Date: Thu, 6 Aug 2026 01:53:09 -0700
Subject: [PATCH] fix: percent-encode index names in per-index remote REST
 paths (#3840)

Nothing validates index names, so a `/` in one is reachable, and the
remote client interpolates it straight into the URL, splitting the path
so the router 404s. The index then reads back as missing and cannot be
dropped, while `create_index` keeps succeeding because it sends the name
in the body.

Encode at the three affected sites, mirroring `fetch_blob_files`. The
shared Rust client covers all bindings.
---
 rust/lancedb/src/remote/table.rs | 50 ++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/rust/lancedb/src/remote/table.rs b/rust/lancedb/src/remote/table.rs
index 5fefabeb2..29b6b698d 100644
--- a/rust/lancedb/src/remote/table.rs
+++ b/rust/lancedb/src/remote/table.rs
@@ -2791,9 +2791,10 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
     }
 
     async fn index_stats(&self, index_name: &str) -> Result<Option<IndexStatistics>> {
+        let encoded_name = urlencoding::encode(index_name);
         let mut request = self.post_read(&format!(
-            "/v1/table/{}/index/{}/stats/",
-            self.identifier, index_name
+            "/v1/table/{}/index/{encoded_name}/stats/",
+            self.identifier
         ));
         let version = self.current_version().await;
         let mut body = serde_json::json!({ "version": version });
@@ -2820,9 +2821,10 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
     }
 
     async fn drop_index(&self, index_name: &str) -> Result<()> {
+        let encoded_name = urlencoding::encode(index_name);
         let request = self.apply_branch_query(self.client.post(&format!(
-            "/v1/table/{}/index/{}/drop/",
-            self.identifier, index_name
+            "/v1/table/{}/index/{encoded_name}/drop/",
+            self.identifier
         )));
         let (request_id, response) = self.send(request, true).await?;
         if response.status() == StatusCode::NOT_FOUND {
@@ -2835,9 +2837,10 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
     }
 
     async fn prewarm_index(&self, index_name: &str) -> Result<()> {
+        let encoded_name = urlencoding::encode(index_name);
         let request = self.client.post(&format!(
-            "/v1/table/{}/index/{}/prewarm/",
-            self.identifier, index_name
+            "/v1/table/{}/index/{encoded_name}/prewarm/",
+            self.identifier
         ));
         let (request_id, response) = self.send(request, true).await?;
         if response.status() == StatusCode::NOT_FOUND {
@@ -6489,6 +6492,41 @@ mod tests {
         assert!(matches!(e, Error::IndexNotFound { .. }));
     }
 
+    /// Index names are unvalidated, so reserved characters must be
+    /// percent-encoded or they restructure the request path.
+    #[tokio::test]
+    async fn test_per_index_paths_encode_reserved_characters() {
+        const NAME: &str = "my/index?a#b c";
+        const PREFIX: &str = "/v1/table/my_table/index/my%2Findex%3Fa%23b%20c";
+
+        let table = Table::new_with_handler("my_table", |request| {
+            assert_eq!(request.url().path(), format!("{PREFIX}/stats/"));
+            let body = serde_json::json!({
+              "num_indexed_rows": 1,
+              "num_unindexed_rows": 0,
+              "index_type": "IVF_PQ",
+              "distance_type": "l2"
+            });
+            http::Response::builder()
+                .status(200)
+                .body(serde_json::to_string(&body).unwrap())
+                .unwrap()
+        });
+        assert!(table.index_stats(NAME).await.unwrap().is_some());
+
+        let table = Table::new_with_handler("my_table", |request| {
+            assert_eq!(request.url().path(), format!("{PREFIX}/drop/"));
+            http::Response::builder().status(200).body("{}").unwrap()
+        });
+        table.drop_index(NAME).await.unwrap();
+
+        let table = Table::new_with_handler("my_table", |request| {
+            assert_eq!(request.url().path(), format!("{PREFIX}/prewarm/"));
+            http::Response::builder().status(200).body("{}").unwrap()
+        });
+        table.prewarm_index(NAME).await.unwrap();
+    }
+
     #[tokio::test]
     async fn test_set_lsm_write_spec_unsharded() {
         let table = Table::new_with_handler("my_table", |request| {