nuvens quebradas
- [USD] USD 67,733.02
- [BRL] BRL 340,859.63 [USD] USD 67,733.02 [GBP] GBP 50,266.36 [EUR] EUR 58,219.78
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.
[02/06/2026 11:23] Governo convoca reunião de emergência para discutir novo tarifaço dos EUA - CNN Brasil
[01/06/2026 20:33] Trump expressou raiva em ligação com Netanyahu sobre planos para o Líbano - CNN Brasil
[02/06/2026 10:01] Médico diz que mulher atacada por tubarão no Recife já saiu do mar sem a perna - O Globo
[02/06/2026 07:00] As intenções de voto de Lula e Flávio Bolsonaro em Mato Grosso, segundo Real Time Big Data - CartaCapital
[02/06/2026 04:04] Mercado terá de se adequar, diz Lewandowski sobre caso PCC/CV - Poder360
[02/06/2026 04:00] Caso Henry: veja os destaques do oitavo dia de julgamento de Jairinho e Monique - O Globo
[02/06/2026 09:26] Quem eram os cinco estudantes mortos em acidente com van em GO - Metrópoles
[02/06/2026 07:29] Corpo achado em Ilhabela é de jovem que sumiu em moto aquática, afirma Marinha - Jovem Pan
[02/06/2026 08:09] Torcida do Galo e manifestantes espalham frases de Vorcaro ao "irmão" Flávio Bolsonaro por BH antes de "ato mais bonito da História" - Revista Fórum
[02/06/2026 12:07] Análise: Novo tarifaço de Trump deve desfazer ajuda a Flávio Bolsonaro com visita à Casa Branca - Valor Econômico