Bitcoin Core

Bitcoin Core 29.4 released

2026-07-13T00:00:00-04:00

Bitcoin Core version 29.4 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 29.4 released was originally published by Bitcoin Core at Bitcoin Core on July 13, 2026.

Bitcoin Core 30.3 released

2026-07-08T00:00:00-04:00

Bitcoin Core version 30.3 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 30.3 released was originally published by Bitcoin Core at Bitcoin Core on July 08, 2026.

Bitcoin Core 31.1 released

2026-07-08T00:00:00-04:00

Bitcoin Core version 31.1 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 31.1 released was originally published by Bitcoin Core at Bitcoin Core on July 08, 2026.

Private Broadcast May Reveal Sender IP Address in Bitcoin Core 31.0

2026-06-06T00:00:00-04:00

We have become aware of a privacy bug in the -privatebroadcast feature, newly introduced in Bitcoin Core 31.0, that may cause the originator’s IP address to be revealed to the receiving peer under certain network conditions. A fix is forthcoming and will be released with 31.1. Users of -privatebroadcast are advised to apply one of the workarounds below until 31.1 is released.

Affected users

This bug affects users where all the following are true:

The node is running Bitcoin Core 31.0 and -privatebroadcast is set.
Transactions are broadcast using the sendrawtransaction RPC. Wallet RPCs (sendtoaddress, sendall, etc.) do not use private broadcast and are not affected.
Tor is reachable for outbound connections.
Outbound IPv4 or IPv6 connections can be made directly. No -onlynet restriction excludes them, and no -proxy=... value applies to them.
BIP324 v2 transport is not disabled with -v2transport=0.

Impact

When private broadcast selects an IPv4 or IPv6 peer that advertises support for v2 (BIP324) transport, the initial connection is routed through the Tor proxy as expected. If the v2 handshake fails on that connection, Bitcoin Core retries it as v1. The v1 retry is not routed through the Tor proxy and instead connects directly to the peer over IPv4 or IPv6, exposing the originator’s IP address to the recipient.

Initial v1 connections (to peers that do not advertise v2) are correctly routed through the Tor proxy and are not affected. The bug is specific to the v1 reconnection that follows a failed v2 handshake. Connections to onion and I2P peers are also unaffected, because they remain routed through their respective proxies on any v1 retry and therefore never expose a clearnet IP address.

This breaks the privacy guarantee stated in the 31.0 release notes: “Their IP address (and thus geolocation) is never known to the recipients”.

How this can happen

A v2 handshake is unlikely to fail for a peer that actually supports v2 transport. The bug is most likely to be triggered by a malicious peer deliberately closing the v2 handshake to force a v1 retry.

Workarounds

Until they can upgrade to 31.1, users of -privatebroadcast should apply one of the following:

Disable the feature. Set -privatebroadcast=0.
Disable v2 transport. Set -v2transport=0. This causes all of the node’s connections to use the unencrypted v1 protocol, which has the downside that it becomes easier to fingerprint and censor on clearnet.
Route IPv4/IPv6 outbound through Tor. Set -proxy=127.0.0.1:9050 (replace 9050 with your Tor SOCKS port if different). This routes all outbound IPv4/IPv6 P2P traffic through Tor exit nodes, which has the downside of making the node easier to Sybil attack.

Credits

Credit to Eugene Siegel for discovering the bug.

Private Broadcast May Reveal Sender IP Address in Bitcoin Core 31.0 was originally published by Bitcoin Core at Bitcoin Core on June 06, 2026.

CVE-2024-52911 - Script Interpreter Remote Crash

2026-05-05T00:00:00-04:00

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 of CScriptCheck functors. Each CScriptCheck holds a pointer to a PrecomputedTransactionData object 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 the PrecomputedTransactionData outlives the CScriptCheck.

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 of PrecomputedTransactionData is destroyed before the CCheckQueueControl.

This is not an issue when the block is valid, as CCheckQueueControl::Wait() will be called before the function returns and the PrecomputedTransactionData gets 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.

CVE-2024-52911 - Script Interpreter Remote Crash was originally published by Bitcoin Core at Bitcoin Core on May 05, 2026.

Bitcoin Core 31.0 released

2026-04-19T00:00:00-04:00

Bitcoin Core version 31.0 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 31.0 released was originally published by Bitcoin Core at Bitcoin Core on April 19, 2026.

Bitcoin Core 28.4 released

2026-03-18T00:00:00-04:00

Bitcoin Core version 28.4 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 28.4 released was originally published by Bitcoin Core at Bitcoin Core on March 18, 2026.

Bitcoin Core 29.3 released

2026-02-10T00:00:00-05:00

Bitcoin Core version 29.3 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 29.3 released was originally published by Bitcoin Core at Bitcoin Core on February 10, 2026.

Bitcoin Core 30.2 released

2026-01-10T00:00:00-05:00

Bitcoin Core version 30.2 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 30.2 released was originally published by Bitcoin Core at Bitcoin Core on January 10, 2026.

Wallet Migration Failure May Delete Unrelated Wallet Files In Bitcoin Core 30.0 and 30.1

2026-01-05T00:00:00-05:00

We have become aware of a wallet migration bug introduced in Bitcoin Core 30.0 and 30.1. Under rare circumstances, when the migration of a wallet.dat file fails, all files in the wallet directory may be deleted in the process, potentially resulting in a loss of funds. A fix is forthcoming and will be released as 30.2, but out of an abundance of caution we have removed the binaries for affected releases from bitcoincore.org.

At this time, we ask users to not attempt wallet migrations using the GUI or RPC until v30.2 is released. All other users, including existing wallet users, are unaffected and can keep using existing installations.

Specifically, it requires the presence of a default (unnamed) wallet.dat file, which has not been created by default since 0.21 (released 5 years ago), that fails to be migrated or loaded. One condition that may trigger this is when pruning is enabled, and the wallet was unloaded while pruning happened.

Wallet Migration Failure May Delete Unrelated Wallet Files In Bitcoin Core 30.0 and 30.1 was originally published by Bitcoin Core at Bitcoin Core on January 05, 2026.

Bitcoin Core 30.1 released

2026-01-02T00:00:00-05:00

Bitcoin Core version 30.1 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 30.1 released was originally published by Bitcoin Core at Bitcoin Core on January 02, 2026.

CVE-2025-46597 - Highly unlikely remote crash on 32-bit systems

2025-10-24T00:00:00-04:00

Disclosure of the details of a bug on 32-bit systems which may, in a rare edge case, cause the node to crash when receiving a pathological block. This bug would be extremely hard to exploit. A fix was released on October 10th 2025 in Bitcoin Core v30.0.

This issue is considered Low severity.

Details

Before writing a block to disk, Bitcoin Core checks that its size is within a normal range. This check would overflow on 32-bit systems for blocks over 1GB, and make the node crash when writing it to disk. Such a block cannot be sent using the BLOCK message, but could in theory be sent as a compact block if the victim node has a non-default large mempool which already contains 1GB of transactions. This would require the victim to have set their -maxmempool option to a value greater than 3GB, while 32-bit systems may have at most 4GiB of memory.

This issue was indirectly prevented by capping the maximum value of the -maxmempool setting on 32-bit systems.

Attribution

Pieter Wuille discovered this bug and disclosed it responsibly.

Antoine Poinsot proposed and implemented a covert mitigation.

Timeline

2025-04-24 - Pieter Wuille reports the issue
2025-05-16 - Antoine Poinsot opens PR #32530 with a covert fix
2025-06-26 - PR #32530 is merged into master
2025-09-04 - Version 29.1 is released with the fix
2025-10-10 - Version 30.0 is released with the fix
2025-10-24 - Public Disclosure

CVE-2025-46597 - Highly unlikely remote crash on 32-bit systems was originally published by Bitcoin Core at Bitcoin Core on October 24, 2025.

CVE-2025-46598 - CPU DoS from unconfirmed transaction processing

2025-10-24T00:00:00-04:00

Disclosure of the details of a resource exhaustion issue when processing an unconfirmed transaction. A fix was released on October 10th 2025 in Bitcoin Core v30.0.

This issue is considered Low severity.

Details

An attacker could send specially-crafted unconfirmed transactions that would take a victim node a few seconds each to validate. The non-standard transactions would be rejected but not lead to a disconnection and the process could be repeated. This could be exploited to delay block propagation.

The issue was mitigated in multiple steps by reducing the validation time in different Script contexts.

Attribution

Antoine Poinsot reported this issue to the Bitcoin Core security mailing list.

Pieter Wuille, Anthony Towns and Antoine Poinsot implemented mitigations to reduce the worst case validation time of unconfirmed transactions.

Timeline

2025-04-25 - Antoine Poinsot reports the issue
2025-05-12 - Pieter Wuille opens PR #32473 to mitigate the worst case quadratic signature hashing in legacy Script context
2025-07-24 - Anthony Towns opens PR #33050 to mitigate the worst case hashing in Tapscript context
2025-07-30 - Antoine Poinsot opens PR #33105 to further mitigate the worst case in legacy Script context
2025-08-08 - PR #33105 is merged into master
2025-08-11 - PR #32473 is merged into master
2025-08-12 - PR #33050 is merged into master
2025-10-10 - Version 30.0 is released with the mitigations
2025-10-24 - Public Disclosure

CVE-2025-46598 - CPU DoS from unconfirmed transaction processing was originally published by Bitcoin Core at Bitcoin Core on October 24, 2025.

CVE-2025-54604 - Disk filling from spoofed self connections

2025-10-24T00:00:00-04:00

Disclosure of the details of a log-filling bug which allowed an attacker to fill up the disk space of a victim node by faking self-connections. Exploitability of this bug is limited, and it would take a long time before it would cause the victim to run out of disk space. A fix was released on October 10th 2025 in Bitcoin Core v30.0.

This issue is considered Low severity.

Details

Bitcoin Core would unconditionally log in case of self-connection. This could be exploited by an attacker by waiting for a victim to connect to it and reusing the version message nonce to establish many connections to the victim, causing it to detect those attempts as self-connections. However, exploitability is limited because the initial connection from the victim will timeout after 60 seconds by default.

This issue was fixed by implementing log rate-limiting across the board, also preventing future issues of the same type from happening.

Attribution

Niklas Goegge discovered this bug and disclosed it responsibly.

Eugene Siegel and Niklas Goegge worked on a fix mitigating all types of log-filling attacks.

Credits also to contributor “practicalswift” who previously raised concerns about disk-filling vectors in Bitcoin Core and worked to address them.

Timeline

2022-03-16 - Niklas Goegge reports this issue to the Bitcoin Core security mailing list
2025-05-23 - Eugene Siegel opens PR #32604 to introduce log rate-limiting, based on earlier work from Niklas Goegge
2025-07-09 - PR #32604 is merged into master
2025-09-04 - Version 29.1 is released with the fix
2025-10-10 - Version 30.0 is released with the fix
2025-10-24 - Public Disclosure

CVE-2025-54604 - Disk filling from spoofed self connections was originally published by Bitcoin Core at Bitcoin Core on October 24, 2025.

CVE-2025-54605 - Disk filling from invalid blocks

2025-10-24T00:00:00-04:00

Disclosure of the details of a log-filling bug which allowed an attacker to cause a victim node to fill up its disk space by repeatedly sending invalid blocks. Exploitability of this bug is limited, as it would take a long time before it would cause the victim to run out of disk space. A fix was released on October 10th 2025 in Bitcoin Core v30.0.

This issue is considered Low severity.

Details

A node would unconditionally log when receiving a block that fails basic sanity checks, or when receiving a block that branches off prior to the last checkpoint. By repeatedly sending such an invalid block to a victim node, an attacker could cause the victim to run out of disk space.

This issue was fixed by implementing log rate-limiting across the board, also preventing future issues of the same type from happening.

Attribution

Niklas Goegge discovered this bug and disclosed it responsibly. Eugene Siegel independently re-discovered this bug and disclosed it responsibly.

Eugene Siegel and Niklas Goegge worked on a fix mitigating all types of log-filling attacks.

Credits also to contributor “practicalswift” who previously raised concerns about disk-filling vectors in Bitcoin Core and worked to address them.

Timeline

2022-05-16 - Niklas Goegge reports this issue to the Bitcoin Core security mailing list
2025-03-13 - Eugene Siegel reports this issue to the Bitcoin Core security mailing list
2025-04-24 - Eugene Siegel reports to the security mailing list about his research on the worst case disk filling rate.
2025-05-23 - Eugene Siegel opens PR #32604 to introduce log rate-limiting, based on earlier work from Niklas Goegge
2025-07-09 - PR #32604 is merged into master
2025-09-04 - Version 29.1 is released with the fix
2025-10-10 - Version 30.0 is released with the fix
2025-10-24 - Public Disclosure

CVE-2025-54605 - Disk filling from invalid blocks was originally published by Bitcoin Core at Bitcoin Core on October 24, 2025.

Bitcoin Core 28.3 released

2025-10-17T00:00:00-04:00

Bitcoin Core version 28.3 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 28.3 released was originally published by Bitcoin Core at Bitcoin Core on October 17, 2025.

Bitcoin Core 29.2 released

2025-10-14T00:00:00-04:00

Bitcoin Core version 29.2 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 29.2 released was originally published by Bitcoin Core at Bitcoin Core on October 14, 2025.

Bitcoin Core 30.0 released

2025-10-10T00:00:00-04:00

Bitcoin Core version 30.0 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 30.0 released was originally published by Bitcoin Core at Bitcoin Core on October 10, 2025.

Bitcoin Core 29.1 released

2025-09-04T00:00:00-04:00

Bitcoin Core version 29.1 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 29.1 released was originally published by Bitcoin Core at Bitcoin Core on September 04, 2025.

Bitcoin Core 28.2 released

2025-06-26T00:00:00-04:00

Bitcoin Core version 28.2 is now available for download. See the release notes for more information about the bug fixes in this release.

If you have any questions, please stop by the #bitcoin IRC chatroom (IRC, web) and we’ll do our best to help you.

Bitcoin Core 28.2 released was originally published by Bitcoin Core at Bitcoin Core on June 26, 2025.