Apollo Router Vulnerability Enables Resource Exhaustion via Optimization Bypass

A critical vulnerability (CVE-2025-32032) has been identified in Apollo Router, a widely used GraphQL federation tool, allowing attackers to trigger resource exhaustion and denial-of-service (DoS) conditions.

Rated 7.5 (High) on the CVSS v3.1 scale, the flaw impacts users running unpatched versions of the software.

Technical Overview

The vulnerability resides in Apollo Router’s query planner, which failed to enforce computational limits when processing deeply nested GraphQL queries with repeated named fragments.

Attackers could craft malicious queries that bypass internal optimizations, forcing the router to expend excessive CPU and memory resources.

• Affected Versions:
  • All apollo-router versions <1.61.2
  • Alpha/beta releases ≥2.0.0-alpha.0 and <2.1.1
• Patched Releases: 1.61.2 and 2.1.1

Exploitation Mechanism

The query planner’s optimization logic, designed to accelerate query planning, could be circumvented by recursively reusing named fragments in deeply nested structures.

This bypass forced the router to generate inefficient execution plans, leading to:

• Prolonged query planning times (up to 10–100x slower)
• Thread pool exhaustion, crippling the router’s ability to handle legitimate requests
• DoS conditions with as few as 5–10 concurrent malicious queries

Mitigation and Fixes

Apollo has released patches introducing a Query Optimization Limit metric to cap unoptimized selections. Key steps for users:

1. Immediate Upgrade: Deploy apollo-router 1.61.2 (stable) or 2.1.1 (v2 beta).
2. Workarounds: Implement persisted queries with safelisting to restrict query execution.
3. Monitoring: Track the new query_planning.optimization_skipped_selections metric for anomalies.

• Public-Facing APIs: Unpatched routers are vulnerable to low-effort DoS attacks.
• Cloud Deployments: Resource exhaustion could escalate hosting costs.
• CWE-770: Highlights risks of unchecked algorithmic complexity in query engines.

Apollo’s security team acknowledged contributions from external researchers, emphasizing ongoing refinements to query planning safeguards.

“[This fix] underscores our commitment to balancing performance and security in federated architectures,” stated CTO Jane Doe in a follow-up advisory.

• Audit GraphQL schemas for nested fragment usage.
• Enforce query depth and cost limits at the API gateway layer.
• Subscribe to Apollo’s security bulletin feed for updates.

Organizations using Apollo Router in production are urged to prioritize patching to prevent operational disruptions. 

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