CVE-2019-25220
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedBitcoin Core before 24.0.1 allows remote attackers to cause a denial of service (daemon crash) via a flood of low-difficulty header chains (aka a "Chain Width Expansion" attack) because a node does not first verify that a presented chain has enough work before committing to store it.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceBitcoin Core before 24.0.1 lacks sufficient validation of proof-of-work before storing header chains received over the P2P network. Attackers can flood a node with low-difficulty header chains, causing excessive memory consumption and eventual daemon crash because the node commits these chains to memory without first verifying they meet the network's work requirement.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 24.0.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check installed Bitcoin Core versionRun 'bitcoin-cli getnetworkinfo' or 'bitcoind --version' to retrieve the version numberAffected if The version is below 24.0.1 (for example, 24.0, 0.21.x, 0.20.x, etc.)
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Confirm Bitcoin Core daemon is runningRun 'bitcoin-cli getblockchaininfo' or check process status with 'ps aux | grep bitcoind'Affected if The daemon is running and actively processing P2P connections
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Inspect memory usage as indirect indicatorMonitor memory consumption via 'bitcoin-cli getmemoryinfo' or system tools like 'top'/'htop' over timeAffected if Unexpectedly high or rapidly growing memory usage, especially after receiving many headers from peers
A user is affected if their Bitcoin Core version is below 24.0.1 and the daemon is running with default P2P networking enabled, which allows external peers to send unverified header chains.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped24.0.1
Upgrade Bitcoin Core to version 24.0.1 or later, which implements proper verification of sufficient work before storing received header chains.
Bitcoin Core 24.0.1
- 1. Backup your wallet.dat file and any important Bitcoin data before upgrading
- 2. Download Bitcoin Core 24.0.1 from the official source at bitcoincore.org
- 3. Verify the downloaded binary using SHA256 checksums and/or GPG signatures as documented on bitcoincore.org
- 4. Stop the running Bitcoin Core daemon: bitcoin-cli stop (or equivalent)
- 5. Install or replace the Bitcoin Core binaries with version 24.0.1
- 6. Restart the Bitcoin Core daemon and verify it is running correctly
- 7. Monitor the logs to ensure the node is functioning properly and syncing
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA6.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,192.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-25220 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-25220 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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