nublado
- [USD] USD 65,965.99
- [BRL] BRL 335,714.12 [USD] USD 65,965.99 [GBP] GBP 49,194.60 [EUR] EUR 56,880.82
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.
[16/06/2026 07:31] A disputa pela presidência entre os eleitores de SP, segundo o Real Time Big Data - CartaCapital
[15/06/2026 20:16] PGR rejeita 2ª proposta delação de Daniel Vorcaro - Poder360
[15/06/2026 12:53] Quem era Oliver Tree, cantor americano morto em acidente de helicóptero no Rio de Janeiro - BBC
[16/06/2026 04:30] Com Bolsonaro preso, campanha de Flávio aposta em legado do pai e reedita estratégia usada pelo PT com Lula em 2018 - O Globo
[15/06/2026 07:14] Irã apresenta 14 exigências para acordo com os EUA - Poder360
[15/06/2026 11:53] G7: com ajudinha de Macron, Lula passará três dias com Trump na França - Metrópoles
[15/06/2026 20:40] Erika Hilton aciona PF por posts sobre jovem morta em rope jump - Poder360
[16/06/2026 06:48] Foragido condenado por crime sexual é preso circulando na Savassi, em BH - Estado de Minas
[16/06/2026 08:37] Quem é Felipe Linares De Oliveira Dell Aquilla, brasileiro suposto ex-chefe do PCC e do CV preso nos EUA - BBC
[16/06/2026 03:35] Super El Niño tem formação captada por satélites espaciais; assista - CNN Brasil