nuvens quebradas
- [USD] USD 73,425.05
- [BRL] BRL 371,538.10 [USD] USD 73,425.05 [GBP] GBP 54,802.40 [EUR] EUR 63,209.20
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.
[27/05/2026 23:07] Fim da escala 6x1:Câmara aprova PEC; como votaram deputados e partidos nos dois turnos - G1
[27/05/2026 20:53] Senado diz que Flávio Bolsonaro não solicitou missão oficial com ônus - CNN Brasil
[27/05/2026 11:39] PL vê palanque de Flávio Bolsonaro ruir no Rio após operações contra Cláudio Castro - CartaCapital
[27/05/2026 19:52] Três explosões são ouvidas em cidade portuária do Irã, diz mídia iraniana - CNN Brasil
[28/05/2026 03:16] Maquiadora disse que 'achava que ia morrer' horas após aplicar PMMA em SP - UOL Notícias
[27/05/2026 19:00] Rival declarado de Gabriel Ganley desiste de competição após morte do fisiculturista: ‘Tudo era em volta da gente’ - Jornal Correio
[27/05/2026 17:55] Fiscais do Enem vão receber até R$ 864 por dia; veja como participar - Jornal Correio
[27/05/2026 18:56] Análise: Trump já ameaçou atacar um em cada 13 países do mundo - CNN Brasil
[28/05/2026 00:01] Caverna onde sobreviventes de enchente estão no Laos tem túneis estreitos e difícil acesso; INFOGRÁFICO - G1
[27/05/2026 18:20] Americanos serão enviados ao Quênia para tratamento de ebola, diz governo Trump - R7