nublado
- [USD] USD 59,726.14
- [BRL] BRL 309,781.59 [USD] USD 59,726.14 [GBP] GBP 45,243.63 [EUR] EUR 52,427.61
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.
[26/06/2026 09:41] A 1ª pesquisa AtlasIntel sobre o vídeo de Michelle contra Flávio Bolsonaro - CartaCapital
[26/06/2026 11:14] Em conjunto, ministros do STF votam para liberar parte do pagamento de penduricalhos - G1
[26/06/2026 17:08] Brasileira de 44 anos é uma das mortas em forte terremoto na Venezuela - CNN Brasil
[26/06/2026 10:34] Marco Rubio mantém tarifas e ignora apelo de Flávio Bolsonaro - Poder360
[26/06/2026 07:41] Josias de Souza: Mendonça cavalga Dark Horse: vai enviar PF à casa de Flávio? - UOL Notícias
[26/06/2026 13:18] Lula diz que está 'cheio de nego maluco no mundo' e afirma que Trump quer tomar Panamá e Groenlândia - G1
[26/06/2026 18:23] Lula cobre nome de Jorginho em placa da BR-470 e fala sobre recusa de recursos para rodovias - NSC Total
[26/06/2026 07:35] Censo Escolar: Brasil reduz índices de reprovação, abandono e atraso - Agência Brasil
[26/06/2026 08:56] Brasil x Japão: Servidores federais serão liberados às 11h na segunda (29) - Correio Braziliense
[26/06/2026 05:03] Mais de 700 bairros de BH e outras sete cidades podem ficar sem água neste domingo; veja lista - G1