nublado
- [USD] USD 62,627.63
- [BRL] BRL 324,721.14 [USD] USD 62,627.63 [GBP] GBP 46,891.00 [EUR] EUR 54,742.06
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.
[03/07/2026 15:16] Durigan diz que PIX não prejudica americanos e defende 'racionalidade' em decisão dos EUA sobre tarifas - G1
[03/07/2026 17:52] Moraes mantém prisão domiciliar humanitária de Jair Bolsonaro - Correio Braziliense
[03/07/2026 22:02] Datafolha: direita supera esquerda pela primeira vez desde 2014, aponta pesquisa - O GLOBO
[04/07/2026 03:30] "Defeso eleitoral" passa a valer hoje para Lula e governadores; entenda - CNN Brasil
[04/07/2026 05:00] Dono de postos que abasteceram carros da campanha de Castro foi alvo da PF, que apura ligação com ex-governador e Bacellar - G1
[03/07/2026 19:58] Michelle Bolsonaro visita PL Mulher e posa para foto com antiga equipe após imagem de papelão viralizar - O GLOBO
[04/07/2026 08:29] Ônibus com romeiros tomba e deixa mortos e feridos no Ceará - G1
[03/07/2026 08:03] PF prende alvo de sanção dos EUA em operação contra PCC - Poder360
[03/07/2026 21:07] Suspeito de atirar em tenente da Rota pode estar em fuga com a família - CNN Brasil
[03/07/2026 14:17] Alerta de perigo: 449 cidades entram na rota de massa polar que trará frio congelante ao Sul do país - NSC Total