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.
Conclusion & alert: CVE-2024-55563 is rated Low Risk (29.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.09%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2025-11-21 | 0.36% | 0.09% | -0.27% |
| 2 | 2025-11-18 | 0.05% | 0.36% | +0.31% |
| 3 | 2025-07-15 | — | 0.05% | — |
Full EPSS history (12 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 5.3 | 3.1 | MEDIUM |
|
3.9 | 1.4 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| bitcoin | bitcoin_core | <= 27.2 | cpe:2.3:a:bitcoin:bitcoin_core:*:*:*:*:*:*:*:* |
| URL | Tags |
|---|---|
| https://ariard.github.io | Third Party Advisory |
| https://bitcoincore.org | Product |
| https://delvingbitcoin.org/t/full-disclosure-transaction-relay-throughput-overflow-attacks-against-off-chain-protocols/1305 | Issue Tracking |
| https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures | Third Party Advisory |
| https://gnusha.org/pi/bitcoindev/CALZpt+EptER=p+P7VN3QAb9n=dODA9_LnR9xZwWpRsdAwedv=w@mail.gmail.com/T/#u | Mailing List |