Apollo Router Unnamed "Subscription" operation results in Denial-of-Service
Date: 2023-09
Affected: rust/apollo-router
Attack vector: info-disclosure
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2023-41317
CWE: CWE-755
CVSS: 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H)

### Impact This is 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. Depending on the environment in which impacted versions are running and the high-availability characteristics of that environment, a single Router's termination may result in limited or reduced availability or other knock-on effects which are deployment-specific (e.g., dependi


Mitigations:

Architectural layers (MAESTRO):