CVE-2024-55563Public exploitNetwork attack vector

HTLC outcome manipulation via transaction-relay jamming

Published Dec 9, 2024 · Updated Mar 4, 2025

Transaction-relay jamming in Bitcoin Core 27.2 and earlier allows remote attackers to delay time-sensitive Lightning transactions. The relay path fee-rate sorts m_tx_inventory_to_send but drains only INVENTORY_BROADCAST_MAX entries, letting higher-fee junk keep a target transaction unannounced. Exploitation requires control of many inbound peers and sustained transaction flooding, allowing an adverse channel counterparty to claim funds after the HTLC timelock expires.

CVSS severity5.3
Medium
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Transaction-relay jamming in Bitcoin Core 27.2 and earlier allows remote attackers to delay time-sensitive Lightning transactions. The relay path fee-rate sorts m_tx_inventory_to_send but drains only INVENTORY_BROADCAST_MAX entries, letting higher-fee junk keep a target transaction unannounced. Exploitation requires control of many inbound peers and sustained transaction flooding, allowing an adverse channel counterparty to claim funds after the HTLC timelock expires.

The record

CVE
CVE-2024-55563
Published
Dec 9, 2024
Updated
Mar 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1498
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1498Network Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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