CVE-2021-41592
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 · uneditedBlockstream c-lightning through 0.10.1 allows loss of funds because of dust HTLC exposure.
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 · moderate confidenceBlockstream c-lightning versions through 0.10.1 contain a vulnerability where dust HTLCs (Hash Time Locked Contracts) can be exposed in a way that allows attackers to cause loss of funds. Dust refers to tiny amounts that may not be economically viable to settle on-chain, and improper handling of these in the HTLC routing logic enables theft or loss of funds.
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<= 0.10.1CVSS 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
- Low
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/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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Identify c-lightning versionRun 'lightningd --version' or check the version file typically found in the installation directory, or use 'cli lightning-cli getinfo' if the daemon is runningAffected if The version returned is 0.10.1 or earlier (any version through 0.10.1)
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Verify c-lightning daemon is runningCheck for running lightningd processes using 'ps aux | grep lightningd' or check service status if running as a systemd serviceAffected if The daemon is running a vulnerable version as identified in step 1
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Inspect HTLC history for dust amountsUse 'lightning-cli listforwards' or check the forwarding/routing database logs for HTLCs with very small amounts (typically below a few hundred satoshis)Affected if Dust-sized HTLCs (amounts not economically viable for on-chain settlement) appear in the HTLC history
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Check recent channel state changesReview channel state using 'lightning-cli listpeers' and examine recent activity logs for any unusual dust HTLC patternsAffected if Channels show recent HTLC activity involving dust amounts that were not properly handled or settled
You are affected if your c-lightning version is 0.10.1 or earlier and there is evidence of dust HTLCs in your routing history or current channel states.
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.
From vendor dataUpgrade c-lightning to version 0.10.2 or later. Review and monitor any recent channel state for suspicious dust HTLCs, and consider closing and recreating channels if compromise is suspected.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-41592 — 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-2021-41592 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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