Description
Bitcoin Core 0.12.0 through 0.21.1 does not properly implement the replacement policy specified in BIP125, which makes it easier for attackers to trigger a loss of funds, or a denial of service attack against downstream projects such as Lightning network nodes. An unconfirmed child transaction with nSequence = 0xff_ff_ff_ff, spending an unconfirmed parent with nSequence <= 0xff_ff_ff_fd, should be replaceable because there is inherited signaling by the child transaction. However, the actual PreChecks implementation does not enforce this. Instead, mempool rejects the replacement attempt of the unconfirmed child transaction.
Metrics
CVSS 3.1 6.5/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:LWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| n/a | n/a | n/a |
References
- https://bitcoinops.org/en/newsletters/2021/05/12/Vendor Advisory
- https://bitcoinops.org/en/topics/replace-by-fee/Vendor Advisory
- https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2021-31876Third Party Advisory
- https://github.com/bitcoin/bitcoinThird Party Advisory
- https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-May/018893.htmlMailing List, Third Party Advisory
- https://bitcoinops.org/en/newsletters/2021/05/12/Vendor Advisory
- https://bitcoinops.org/en/topics/replace-by-fee/Vendor Advisory
- https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2021-31876Third Party Advisory
- https://github.com/bitcoin/bitcoinThird Party Advisory
- https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2021-May/018893.htmlMailing List, Third Party Advisory
Timeline
- Published
- May 13, 2021
- Last modified
- Jun 17, 2026
- NVD status
- Modified