CVE-2023-41317: Improper Handling of Exceptional Conditions (CWE-755)
value: The Apollo Router is a configurable, high-performance graph router written in Rust to run a federated supergraph that uses Apollo Federation 2. Affected versions are subject to a Denial-of-Service (DoS) type vulnerability which causes the Router to panic and terminate when GraphQL Subscriptions are enabled.  It can be triggered when **all of the following conditions are met**: 1. Running Apollo Router v1.28.0, v1.28.1 or v1.29.0 ("impacted versions"); **and** 2. The Supergraph schema provided to the Router (either via Apollo Uplink or explicitly via other configuration) **has a `subscription` type** with root-fields defined; **and** 3. The YAML configuration provided to the Router **has subscriptions enabled** (they are _disabled_ by default), either by setting `enabled: true` _or_ by setting a valid `mode` within the `subscriptions` object (as seen in [subscriptions' documentation](https://www.apollographql.com/docs/router/executing-operations/subscription-support/#router-setup)); **and** 4. An [anonymous](https://spec.graphql.org/draft/#sec-Anonymous-Operation-Definitions) (i.e., un-named) `subscription` operation (e.g., `subscription { ... }`) is received by the Router If **all four** of these criteria are met, the impacted versions will panic and terminate.  There is no data-privacy risk or sensitive-information exposure aspect to this vulnerability. This is fixed in Apollo Router v1.29.1. Users are advised to upgrade. Updating to v1.29.1 should be a clear and simple upgrade path for those running impacted versions.  However, if Subscriptions are **not** necessary for your Graph – but are enabled via configuration — then disabling subscriptions is another option to mitigate the risk.
CWE description: The product does not handle or incorrectly handles an exceptional condition.
CVSS v3 base score: 5.9
Published: 2023-09-05T19:15Z
Repository: https://github.com/apollographql/router
Language: Rust
Files changed: .changesets/fix_dragonfly_ship_win_folder.md, apollo-router/src/context/mod.rs, apollo-router/src/services/subgraph_service.rs
Commit date: 2023-09-04 16:35:03 +0000
Commit message: Subscriptions: Correct v1.28.x regression allowing panic via un-named subscription operation (#3738)

### Subscriptions: Correct v1.28.x regression allowing panic via un-named subscription operation

Correct a regression that was introduced in Router v1.28.0 which made a Router **panic** possible when the following _three_ conditions are _all_ met:

1. When sending an un-named (i.e., "anonymous") `subscription` operation (e.g., `subscription { ... }`); **and**;
2. The Router has a `subscription` type defined in the Supergraph schema; **and**
3. Have subscriptions enabled (they are disabled by default) in the Router's YAML configuration, either by setting `enabled: true` _or_ by setting a `mode` within the `subscriptions` object (as seen in [the subscriptions documentation]
Diff: diff --git a/.changesets/fix_dragonfly_ship_win_folder.md b/.changesets/fix_dragonfly_ship_win_folder.md
new file mode 100644
index 00000000..892df675
--- /dev/null
+++ b/.changesets/fix_dragonfly_ship_win_folder.md
@@ -0,0 +1,9 @@
+### Subscriptions: Correct v1.28.x regression allowing panic via un-named subscription operation
+
+Correct a regression that was introduced in Router v1.28.0 which made a Router **panic** possible when the following _three_ conditions are _all_ met:
+
+1. When sending an un-named (i.e., "anonymous") `subscription` operation (e.g., `subscription { ... }`); **and**;
+2. The Router has a `subscription` type defined in the Supergraph schema; **and**
+3. Have subscriptions enabled (they are disabled by default) in the Router's YAML configuration, either by setting `enabled: true` _or_ by setting a `mode` within the `subscriptions` object (as seen in [the subscriptions documentation](https://www.apollographql.com/docs/router/executing-operations/subscription-support/#router-setup).
+
+By [@o0Ignition0o](https://github.com/o0Ignition0o) in https://github.com/apollographql/router/pull/3738
diff --git a/apollo-router/src/context/mod.rs b/apollo-router/src/context/mod.rs
index 07042e08..83bdb2bc 100644
--- a/apollo-router/src/context/mod.rs
+++ b/apollo-router/src/context/mod.rs
@@ -68,17 +68,10 @@ impl Context {
         }
     }
 }
 
 impl Context {
-    pub(crate) fn operation_name(&self) -> Option<String> {
-        // This method should be removed once we have a proper way to get the operation name.
-        self.entries
-            .get(OPERATION_NAME)
-            .map(|v| v.value().as_str().unwrap().to_string())
-    }
-
     /// Returns true if the context contains a value for the specified key.
     pub fn contains_key<K>(&self, key: K) -> bool
     where
         K: Into<String>,
     {
diff --git a/apollo-router/src/services/subgraph_service.rs b/apollo-router/src/services/subgraph_service.rs
index e137177a..c99e4827 100644
--- a/apollo-router/src/services/subgraph_service.rs
+++ b/apollo-router/src/services/subgraph_service.rs
@@ -429,10 +429,17 @@ async fn call_websocket(
     context: Context,
     service_name: String,
     subgraph_cfg: &WebSocketConfiguration,
     subscription_hash: String,
 ) -> Result<SubgraphResponse, BoxError> {
+    let operation_name = request
+        .subgraph_request
+        .body()
+        .operation_name
+        .clone()
+        .unwrap_or_default();
+
     let SubgraphRequest {
         subgraph_request,
         subscription_stream,
         ..
     } = request;
@@ -443,11 +450,10 @@ async fn call_websocket(
         })?;
 
     let (handle, created) = notify
         .create_or_subscribe(subscription_hash.clone(), false)
         .await?;
-    let operation_name = context.operation_name().unwrap_or_default();
     tracing::info!(
         monotonic_counter.apollo.router.operations.subscriptions = 1u64,
         subscriptions.mode = %"passthrough",
         subscriptions.deduplicated = !created,
         subgraph.service.name = service_name,

Vulnerable code:     pub(crate) fn operation_name(&self) -> Option<String> {
        // This method should be removed once we have a proper way to get the operation name.
        self.entries
            .get(OPERATION_NAME)
            .map(|v| v.value().as_str().unwrap().to_string())
    }

    let operation_name = context.operation_name().unwrap_or_default();
Fixed code: ### Subscriptions: Correct v1.28.x regression allowing panic via un-named subscription operation

Correct a regression that was introduced in Router v1.28.0 which made a Router **panic** possible when the following _three_ conditions are _all_ met:

1. When sending an un-named (i.e., "anonymous") `subscription` operation (e.g., `subscription { ... }`); **and**;
2. The Router has a `subscription` type defined in the Supergraph schema; **and**
3. Have subscriptions enabled (they are disabled by default) in the Router's YAML configuration, either by setting `enabled: true` _or_ by setting a `mode` within the `subscriptions` object (as seen in [the subscriptions documentation](https://www.apollographql.com/docs/router/executing-operations/subscription-support/#router-setup).

By [@o0Ignition0o](https://github.com/o0Ignition0o) in https://github.com/apollographql/router/pull/3738
    let operation_name = request
        .subgraph_request
        .body()
        .operation_name
        .clone()
        .unwrap_or_default();