nuvens quebradas
- [USD] USD 77,858.58
- [BRL] BRL 389,425.28 [USD] USD 77,858.58 [GBP] GBP 57,915.34 [EUR] EUR 66,950.99
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.
[20/05/2026 23:05] PF rejeita delação de Daniel Vorcaro por falta de informações relevantes - Folha de S.Paulo
[20/05/2026 22:05] Aliados veem vitória de Marinho em troca de marqueteiro de Flávio - CNN Brasil
[21/05/2026 00:02] Zema muda tom e diz aguardar explicação de Flávio sobre Vorcaro - Poder360
[20/05/2026 21:10] Trump e Netanyahu divergem sobre guerra com o Irã em conversa tensa - CNN Brasil
[20/05/2026 18:52] Homem morre, e mulheres e bebê de 1 ano são baleados em ataque de criminosos em Costa Barros, no Rio - G1
[20/05/2026 18:36] Relator da PEC da escala 6x1 defende que quem recebe acima de R$ 16 mil não tenha limite de jornada de trabalho - O Globo
[20/05/2026 17:16] Marco Civil da Internet: o que muda com as novas regras para big techs - CNN Brasil
[20/05/2026 20:44] Inmet intensifica alerta para frio congelante em 90 cidades do Brasil - NSC Total
[20/05/2026 17:37] Manifestação estudantil fecha Faria Lima contra Governo de SP - CNN Brasil
[20/05/2026 16:25] Tentativas de uso de prompt injection no STJ serão investigadas - STJ