fix: don't try to serve states for future slots #8665
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Summary of ChangesHello @nflaig, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request introduces a critical security enhancement by preventing beacon nodes from attempting to serve state data for future blockchain slots. Previously, requesting a state for a slot far ahead of the current head could lead to an unbounded amount of computational work, making the node vulnerable to Denial-of-Service attacks. The changes ensure that any such requests are immediately rejected with a "not found" error, thereby safeguarding the node's resources and stability. Highlights
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Code Review
This pull request correctly addresses a potential denial-of-service vulnerability by preventing state lookups for future slots. The logic is sound and the change is targeted. I have one suggestion to refactor the nested ternary operators into a more readable if/else structure, which should improve the maintainability of the code.
twoeths
approved these changes
Dec 3, 2025
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Performance Report✔️ no performance regression detected Full benchmark results
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wemeetagain
approved these changes
Dec 3, 2025
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## unstable #8665 +/- ##
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Coverage 52.02% 52.02%
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Files 848 848
Lines 65837 65834 -3
Branches 4811 4810 -1
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- Hits 34250 34249 -1
+ Misses 31518 31516 -2
Partials 69 69 🚀 New features to boost your workflow:
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🎉 This PR is included in v1.38.0 🎉 |
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Motivation
When requesting a future slot the node tries to dial the state from head which allows to quite easily DoS the node as it's unbounded amount of work if the slot is very far away from head.
We should not allow to request states that are in the future (> clock slot) and return a 404 instead.
Description
In case state is request by slot, check if it's a slot from the future based on clock slot and return 404 state not found error.
I didn't use
forkChoice.getHead().slotbecause we should still be able to serve the state if all slots between the requested slot and the head slot are skipped.Related discord discussion, thanks to @guha-rahul for catching and reporting this.