Mempool

The memory pool maintained by each blockchain node holding broadcast but as-yet unconfirmed transactions awaiting inclusion in a block. Miners select transactions from the mempool, typically prioritising by fee rate, while node operators use mempool policies to manage capacity and mitigate spam.

Semantic Classification

Content

Class Declaration

Declaration(Class(:Mempool))

Subclass Relationships

SubClassOf(:Mempool :DistributedDataStructure) SubClassOf(:Mempool :BlockchainEntity)

Essential Properties

SubClassOf(:Mempool (ObjectSomeValuesFrom :partOf :Blockchain))

SubClassOf(:Mempool (ObjectSomeValuesFrom :hasProperty :Property))

Data Properties

DataPropertyAssertion(:hasIdentifier :Mempool “BC-0019”^^xsd:string) DataPropertyAssertion(:hasAuthorityScore :Mempool “1.0”^^xsd:decimal) DataPropertyAssertion(:isFoundational :Mempool “true”^^xsd:boolean)

Object Properties

ObjectPropertyAssertion(:enablesFeature :Mempool :BlockchainFeature) ObjectPropertyAssertion(:relatesTo :Mempool :RelatedConcept)

Annotations

AnnotationAssertion(rdfs:label :Mempool “Mempool”@en) AnnotationAssertion(rdfs:comment :Mempool “Memory pool of pending transactions”@en) AnnotationAssertion(dct:description :Mempool “Foundational blockchain concept with formal ontological definition”@en) AnnotationAssertion(:termID :Mempool “BC-0019”) AnnotationAssertion(:priority :Mempool “1”^^xsd:integer) AnnotationAssertion(:category :Mempool “blockchain-fundamentals”@en) )

About Mempool

• Memory pool of pending transactions within blockchain systems, providing essential functionality for distributed ledger technology operations and properties.

Key Characteristics

• 1. Definitional Property: Core defining characteristic
• 2. Functional Property: Operational behavior
• 3. Structural Property: Compositional elements
• 4. Security Property: Security guarantees provided
• 5. Performance Property: Efficiency considerations

Technical Components

• Implementation: How concept is realized technically
• Verification: Methods for validating correctness
• Interaction: Relationships with other components
• Constraints: Technical limitations and requirements

Use Cases

• 1. Core Blockchain Operation
• Application: Fundamental blockchain functionality
• Example: Practical implementation in major blockchains
• Requirements: Technical prerequisites
• Benefits: Value provided to blockchain systems

Standards & References

• IEC 23257:2021 - Blockchain and distributed ledger technologies
• IEEE 2418.1 - Blockchain and distributed ledger technologies
• NIST NISTIR - Blockchain and distributed ledger technologies

Current Landscape (2026)

• The public mempool has been largely hollowed out as a transaction pathway: by 2026 roughly 80% of Ethereum DeFi order flow bypasses it entirely, routing through private RPCs (MEV-Blocker, Flashbots Protect, Merkle, Blink and Polygon’s Private Mempool) and order-flow auctions rather than being broadcast to all nodes.
• Encrypted mempools have moved from research to concrete standardisation: EIP-8105 “Universal Enshrined Encrypted Mempool” (Shutter’s Jannik Luhn, published 17 December 2025) proposes a scheme-agnostic native encrypted transaction type (0x05 encrypted, 0x06 decrypted under EIP-2718) that hides payloads until block ordering is fixed, supporting threshold encryption, MPC, TEEs, delay encryption or FHE.
• A competing design, EIP-8184 “LUCID” (created 4 March 2026), offers a public encrypted mempool built on commit-before-reveal with delayed decryption, keeping MEV-sensitive flow on a permissionless inclusion path rather than in trusted private channels; both are being weighed for Ethereum’s next upgrade cycle (Glamsterdam/Hegotá).
• Proposer-builder separation is being enshrined in-protocol: EIP-7732 (ePBS) is the headline feature of the Glamsterdam upgrade targeted for the back half of 2026, replacing off-chain MEV-Boost relays (currently carrying 80-90% of blocks) with an in-protocol commit-reveal handoff and a Payload Timeliness Committee.
• Decentralised, TEE-based block building consolidated around BuilderNet (launched November 2024, jointly run by Flashbots, Beaverbuild and Nethermind); by 5 December 2024 Flashbots had migrated all order flow to it and shut down its centralised builders, reaching BuilderNet v1.2 with reproducible Intel TDX images in February 2025.
• Builder centralisation remains the core open challenge: with PBS adoption near-universal (~93% of blocks), the top three builders produce 80-95% of PBS blocks, and the 4 December 2025 Prysm circuit-breaker incident collapsed PBS block share from ~90% to near-zero, exposing supply-chain fragility.
• Private routing is proving to be no guaranteed shield: a December 2025 arXiv study documented 2,932 sandwich attacks on 3,126 private transactions (Nov-Dec 2024, ~$409kuserlosses),andMEVbotsstillextractedaround$24 million in a single 30-day window over December 2025-January 2026.

References

• 1. Shutter Network (2025). Introducing EIP-8105 Universal Enshrined Encrypted Mempool. https://blog.shutter.network/introducing-the-universal-enshrined-encrypted-mempool-eip/
• 2. Ethereum (Luhn, J.) (2025). EIP-8105: Universal Enshrined Encrypted Mempool. https://eips.ethereum.org/EIPS/eip-8105
• 3. Ethereum (2026). EIP-8184: LUCID encrypted mempool. https://eips.ethereum.org/EIPS/eip-8184
• 4. BlockEden.xyz (2026). Fighting MEV in 2026: How MEV-Blocker, BuilderNet, and CoW Swap Protect DeFi. https://blockeden.xyz/blog/2026/05/02/mempool-privacy-mev-blocker-flashbots-suave-cowswap-defi-protection/
• 5. The Off-Chain Thoughts (2026). MEV, Encrypted Mempools, and the Execution Layer. https://theoffchainthoughts.substack.com/p/the-cartel-we-renamed-mev-encrypted
• 6. Sandwiched and Silent: Behavioral Adaptation and Private Channel Exploitation (2025). arXiv. https://arxiv.org/html/2512.17602v1

Provenance