CVE-2025-32031

Executive Summary

CVE-2025-32031 is a high-severity denial-of-service (DoS) vulnerability in Apollo Gateway, a GraphQL gateway that aggregates multiple GraphQL microservices. The flaw allows an unauthenticated attacker to craft queries with deeply nested and reused named fragments, causing the query planner to consume excessive CPU and memory resources. This can render the gateway inoperable, leading to a denial of service. The vulnerability is present in all versions prior to 2.10.1. The patch is available in version 2.10.1, which introduces a timeout mechanism for query planning.

Supply Chain & Package Security

This vulnerability affects the @apollo/gateway npm package. Organizations using Apollo Gateway in their GraphQL infrastructure should immediately audit their dependency tree for affected versions. The package is widely used in Node.js microservices architectures. The fix is a non-breaking upgrade, but teams should test their GraphQL schemas and queries after patching to ensure compatibility.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: None (I:N)
• Availability Impact: High (A:H)

The vulnerability is remotely exploitable without authentication, making it a significant threat to availability. The low attack complexity means that even unsophisticated attackers can craft malicious queries.

Deep Dive & Mechanics

Apollo Gateway’s query planner optimizes GraphQL queries by flattening and reusing selections. However, when a query contains deeply nested and reused named fragments, the planner’s internal optimization is bypassed. This forces the planner to process an exponential number of selection combinations, leading to excessive CPU and memory consumption.

The core issue lies in the buildPlan function, which recursively processes fragments. Without a timeout, a single malicious query can consume all available resources, effectively performing a denial-of-service attack.

Vulnerable vs. Patched Code

Vulnerable Code (simplified):

function buildPlan(selections) {
  for (const selection of selections) {
    if (selection.kind === 'FragmentSpread') {
      // No timeout, no depth limit
      buildPlan(expandFragment(selection));
    }
  }
}

Patched Code (simplified):

function buildPlan(selections, timeout) {
  const start = Date.now();
  for (const selection of selections) {
    if (Date.now() - start > timeout) {
      throw new Error('Query planning timed out');
    }
    if (selection.kind === 'FragmentSpread') {
      buildPlan(expandFragment(selection), timeout);
    }
  }
}

The patch introduces a configurable timeout (default 30 seconds) that aborts query planning if it exceeds the limit. This prevents resource exhaustion.

Exploitation & Lab Setup

Red Team

To simulate the attack, an attacker would send a GraphQL query with deeply nested fragments. Example:

query MaliciousQuery {
  field1 {
    ...FragmentA
    ...FragmentB
  }
}
fragment FragmentA on Type {
  nested1 {
    ...FragmentA
    ...FragmentB
  }
}
fragment FragmentB on Type {
  nested2 {
    ...FragmentA
    ...FragmentB
  }
}

This query can be sent repeatedly to amplify the effect. The attacker does not need authentication.

Blue Team

To detect and mitigate this attack:

1. Rate Limiting: Implement rate limiting on the GraphQL endpoint to restrict the number of queries per IP.
2. Query Complexity Analysis: Use tools like graphql-query-complexity to reject overly complex queries.
3. Timeout Enforcement: Ensure the gateway is patched to version 2.10.1 or later.
4. Monitoring: Monitor CPU and memory usage on gateway nodes. Alert on sustained high usage.

Indicators of Compromise (IOCs)

• Network: Unusually high number of GraphQL queries with deeply nested fragments.
• Logs: Gateway logs showing repeated query planning failures or timeouts.
• System: High CPU and memory usage on Apollo Gateway instances.
• File: No specific file-based IOCs.

Detection Engineering

YARA Rule

rule CVE_2025_32031_GraphQL_DoS {
  meta:
    description = "Detects malicious GraphQL queries exploiting CVE-2025-32031"
    author = "Valters IT"
    date = "2025-04-01"
    severity = "high"
  strings:
    $fragment = /fragment\s+\w+\s+on\s+\w+\s*\{[^}]*\{[^}]*\{/ nocase
    $nested = /\.\.\.\w+.*\.\.\.\w+/ nocase
  condition:
    any of them
}

Sigma Rule

title: Apollo Gateway DoS via Deeply Nested Fragments
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential exploitation of CVE-2025-32031
logsource:
  category: application
  product: apollo_gateway
detection:
  selection:
    event: "query_planning_timeout"
  condition: selection
falsepositives:
  - Legitimate complex queries
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-32031 Apollo Gateway DoS Attempt"; flow:to_server; content:"query"; http_client_body; pcre:"/fragment\s+\w+\s+on\s+\w+\s*\{[^}]*\{[^}]*\{/"; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Patch: Upgrade @apollo/gateway to version 2.10.1 or later.
2. Workaround: If patching is not possible, implement a reverse proxy with query complexity limits.
3. Network Controls: Use Web Application Firewall (WAF) rules to block queries with excessive nesting.
4. Monitoring: Enable logging for query planning timeouts and set up alerts.
5. Rate Limiting: Apply rate limiting per client IP to reduce attack surface.

Valters IT
Securing Digital Frontiers