nublado
- [USD] USD 63,186.86
- [BRL] BRL 327,620.72 [USD] USD 63,186.86 [GBP] GBP 47,309.71 [EUR] EUR 55,230.88
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.
[04/07/2026 03:55] PF vê prejuízo após ação dos EUA em investigação sobre o PCC - Correio Braziliense
[03/07/2026 21:25] Nikolas diz que pode mediar atrito entre Flávio e Michelle - Poder360
[04/07/2026 04:19] O que sabemos sobre o evento de fogos de artifício de 4 de julho de Trump - CNN Brasil
[04/07/2026 07:00] Mutretas de aliados afundam mais a candidatura de Flávio Bolsonaro - Intercept Brasil
[04/07/2026 09:00] Regras do período de defeso eleitoral começam a valer neste sábado - CartaCapital
[04/07/2026 11:21] Guerra na Ucrânia: Rússia recorre a estudantes para repor as crescentes baixas na Ucrânia - BBC
[04/07/2026 09:14] Com 2 mortes, vítimas do ônibus que tombou com romeiros em Canindé eram da mesma família - O POVO
[03/07/2026 19:35] Ex-mulher de goleiro Bruno está desaparecida desde 5ª feira - Poder360
[04/07/2026 07:30] Até -5°C e alerta de geada: massa de ar polar faz temperaturas despencarem neste sábado (4) - ND Mais
[04/07/2026 12:09] Datafolha: 70% da população defende punir menores infratores como adultos - CNN Brasil