nevoeiro
- [USD] USD 80,979.57
- [BRL] BRL 397,949.79 [USD] USD 80,979.57 [GBP] GBP 59,380.05 [EUR] EUR 68,620.95
Price index provided by blockchain.info. - After Bitcoin Core 0.14.0 and before Bitcoin Core 29.0, validating a specially-crafted block may cause the node to access previously freed memory.
During validation, necessary data required for checking inputs for each transaction is pre-calculated and cached. For specially crafted invalid blocks, it was possible for this data to be destroyed while it was still being accessed by a background validation thread. An attacker capable of mining a block with sufficient proof-of-work could have exploited this to crash victim nodes. Because of the nature of use-after-free bugs, it is possible that the crash could have been used for remote code execution, though constraints on the input (block) data make this unlikely.
This issue is considered High severity.
Details
By default, script validation for new blocks is dispatched to background threads via a vector ofCScriptCheckfunctors. Each CScriptCheck holds a pointer to aPrecomputedTransactionDataobject which stores some data needed by each input in the transaction. Because it stores a pointer and not the data itself, care must be taken to ensure that thePrecomputedTransactionDataoutlives theCScriptCheck.
The script checks lifetime is enforced by an RAII class,CCheckQueueControl. However, the control is intantiated before the precomputed transaction data. Because local objects in C++ are destructed in reverse order of construction, this means the vector ofPrecomputedTransactionDatais destroyed before theCCheckQueueControl.
This is not an issue when the block is valid, asCCheckQueueControl::Wait()will be called before the function returns and thePrecomputedTransactionDatagets destroyed. However, in case of an early return (when a separate check fails) a background script thread may read the precomputed transaction data after it was destroyed. An attacker could exploit this to crash victim nodes at the expense of a valid PoW at tip.
Attribution
Cory Fields (MIT DCI) discovered this vulnerability and responsibly disclosed it in a detailed report containing a proof of concept for reproduction and a proposed mitigation.
Timeline
- 2024-11-02 Cory Fields privately reports the bug
- 2024-11-06 Pieter Wuille pushes a covert fix to already open PR #31112 which works around the issue by removing the early returns
- 2024-12-03 PR #31112 is merged
- 2025-04-12 Bitcoin Core version 29.0 is released with a fix
- 2026-04-19 The last vulnerable Bitcoin Core version (28.x) goes end of life
- 2026-05-05 Public disclosure.
[10/05/2026 09:25] Vídeo mostra como é o cruzeiro que teve surto de hantavírus - ND Mais
[10/05/2026 09:07] PF investiga compra de triplex de R$ 22 mi por Ciro Nogueira - Poder360
[10/05/2026 08:20] PM retira estudantes que invadiram reitoria da USP - O Antagonista
[09/05/2026 18:32] O que revelam documentos sobre óvnis divulgados pelo Pentágono - BBC
[10/05/2026 08:06] Kassio tenta blindagem no TSE e mira se diferenciar de Moraes - Estado de Minas
[10/05/2026 11:35] Corredor polar se abre e trará sequência de massas de ar frio - MetSul Meteorologia
[09/05/2026 20:52] Suspensão da Lei da Dosimetria por Moraes pode se arrastar por anos - Gazeta do Povo
[10/05/2026 08:22] Acidente grave em Diamantina: prefeitura pede doação de sangue para vítimas - Estado de Minas
[10/05/2026 09:30] Tiago Mali: Presidente não recuperará mais controle de emendas, diz criador de pesquisa - UOL Notícias
[10/05/2026 01:20] Israel deporta ativista brasileiro que estava em flotilha para Gaza - CNN Brasil