The peer-to-peer network: relay, propagation, nodes and the Lightning layer.
14 publications
By pretending not to support BIP 31 pings, a malicious peer could dodge the 20-minute disconnect and read slowly, swelling a node's send queue by up to 2MB per hour for each inbound peer and 5MB for each outbound one. CVE-2026-117349, rated Medium, is fixed by #36667 in Bitcoin Core 32.1, 31.2, 30.4 and 29.5; -blocksonly nodes were much less exposed.
Bitcoin Core
Faked self-connections let an attacker pad a Bitcoin Core node's log files by reusing the version message nonce across many connections. The victim's first connection times out after 60 seconds by default, so filling a disk would take a long time; CVE-2025-54604 is rated Low. Niklas Goegge reported it in 2022, and log rate-limiting in 29.1 and 30.0 stops it.
Bitcoin Core
Thirty-one Bitcoin Core contributors signed a letter saying node software should not refuse to relay transactions with sustained economic demand that reliably reach blocks, since users and miners can route around such filters. They stress this does not endorse non-financial data use and that users alone choose which software and policies to run.
Bitcoin Core
Years of nonstop addr spam could overflow the 32-bit identifier in Bitcoin Core's address manager and crash the node, the remainder of an attack first blunted by rate limiting in v22.0. Version 29.0 moves to a 64-bit identifier, closing CVE-2024-52919, rated Low. Eugene Siegel found it; Martin Zumsande made the change.
Bitcoin Core
A peer that announces a block and then stalls could leave a Bitcoin Core node waiting up to 10 minutes before trying elsewhere, and attackers could repeat the trick. CVE-2024-52922, rated Medium and reported and fixed by Greg Sanders, is mitigated in v25.1 and v26.0, which can request a block at once from as many as 3 high-bandwidth compact block peers.
Bitcoin Core
A burst of network activity in early May 2023, made worse by spy nodes, slowed block and transaction propagation as sorting oversized inv-to-send sets ate nearly all of the P2P thread's time. Rated Medium, the problem was fixed in Bitcoin Core v25.0 by #27610, which drops transactions gone from the mempool sooner and drains the sets faster as they grow.
Bitcoin Core
Mutated blocks from one peer could wipe the download state of other peers announcing the same block in Bitcoin Core before v25.0, making a node forget a compact block it was still reconstructing. Suhas Daftuar noticed the problem, and #27608 limits each peer to its own state. CVE-2024-52921 is rated Medium.
Bitcoin Core
Chains of low-difficulty headers could remotely crash Bitcoin Core nodes before v24.0.1, and one crafted chain could be reused against any node on the network. The fix in #25717 makes a node check that a chain carries enough work before storing it, which also ended reliance on checkpoints against known attacks. Severity: High.
Bitcoin Core
Spamming addr messages could crash a Bitcoin Core node: 2^32 addrman insertions overflowed a 32-bit ID counter and tripped an assertion. Eugene Siegel reported the High-severity bug in 2021, and v22.0 carries Pieter Wuille's fix.
Bitcoin Core
Two bugs in version message handling, a signed-integer overflow and an abs64 logic error, let an attacker skew a victim's adjusted time until it rejected new blocks as dated too far in the future. The attacker had to be among the first 200 peers to connect. Rated Medium, the flaw was fixed in Bitcoin Core 0.21.0.
Bitcoin Core
A malformed GETDATA message could leave the net_processing thread spinning at 100% CPU in Bitcoin Core versions before 0.20.0, adding 1.5 MB of memory per attacking peer. Other peers kept being served, hence the Low rating. John Newbery found the bug and fixed it in #18808.
Bitcoin Core
One INV packed with 50,000 block items could make a node queue 50,000 getheaders responses of about 1 kB each, and a peer refusing to read them kept that 50 MB send buffer full. John Newbery's #18962, pitched as a bandwidth saving, sent one GETHEADERS per INV and shipped in 0.20.0.
Bitcoin Core
Tor users can now reach the Bitcoin Core website through an onion address, following frequent requests. The hidden service adds another route around censorship and a trust path that depends on neither certificate authorities nor DNS.
Bitcoin Core
Peers using compact block relay (BIP152) exchange a sketch of each new block, about 9KB for an average 1MB block, plus overhead for transactions the receiver lacks. In live high-bandwidth experiments with up to 6 prefilled transactions, well over 90% of blocks propagated with no follow-up request.
Bitcoin Core
