Bug 2548316 (CVE-2026-107727)

Summary: CVE-2026-107727 strawberry-graphql: strawberry-graphql: Denial of service via uncleared completed subscriptions
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in strawberry-graphql, which could lead to a denial of service (DoS) on affected connections. When a limit on subscriptions per connection is configured, the legacy subscription handler fails to properly remove completed operations from internal tracking. A remote client can exhaust the allocated connection slots by sending multiple short-lived subscription requests over a persistent connection, causing subsequent legitimate operations on that connection to be rejected.
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Description OSIDB Bzimport 2026-10-08 22:31:44 UTC 
Strawberry GraphQL is a library for creating GraphQL APIs. From 0.312.3 until 0.327.2, the legacy graphql-ws subscription handler in strawberry/subscriptions/protocols/graphql_ws/handlers.py does not remove naturally completed operations from self.tasks and self.subscriptions. When max_subscriptions_per_connection is configured, a client on a persistent WebSocket connection can use distinct operation IDs for one-shot subscriptions to fill the connection's configured slots even after those subscriptions send complete, causing later legitimate operations on that connection to be rejected with Subscription limit reached. The modern graphql-transport-ws protocol and deployments without the configured per-connection cap are not affected. This issue is fixed in version 0.327.2.