CVE-2024-55563: Bitcoin Core

Medium severity, CVSS 5.3. EPSS: 0.7% chance of exploitation in the next 30 days.

Bitcoin Core through 27.2 allows transaction-relay jamming via an off-chain protocol attack, a related issue to CVE-2024-52913. For example, the outcome of an HTLC (Hashed Timelock Contract) can be changed because a flood of transaction traffic prevents propagation of certain Lightning channel transactions.

Affected products

• Bitcoin Bitcoin Core: up to and including 27.2

Published 2024-12-09. Last modified 2026-06-17.