CVE-2021-41592: Blockstream c-lightning through 0.10.1 allows loss of funds because of dust HTLC exposure.

Q: How do I fix CVE-2021-41592?

c-lightning: upgrade to newer than 0.10.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-41592 being exploited?

CVE-2021-41592 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-41592 affect?

CVE-2021-41592 affects c-lightning. Severity is critical (CVSS 9.4). Blockstream c-lightning through 0.10.1 allows loss of funds because of dust HTLC exposure.

Q: How urgent is CVE-2021-41592?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.4REMOTEUPGRADE

CVE-2021-41592 is a critical-severity flaw (CVSS 9.4) affecting c-lightning. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Blockstream c-lightning through 0.10.1 allows loss of funds because of dust HTLC exposure.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.4 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Weakness	CWE-770
Published	2021-10-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: elementsproject

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-10-04 17:15 UTCPublished CVE record published
2026-06-17 04:08 UTCUpdated Record last modified

elementsproject c-lightning UPGRADE

Affected: <= 0.10.1

Fixed in: newer than 0.10.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy c-lightning || rpm -q c-lightning || c-lightning --version

2. UPGRADE to newer than 0.10.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade c-lightning

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade c-lightning

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-41592?

c-lightning: upgrade to newer than 0.10.1. Exact commands for each OS are on this page.

Is CVE-2021-41592 being exploited?

CVE-2021-41592 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-41592 affect?

CVE-2021-41592 affects c-lightning. Severity is critical (CVSS 9.4). Blockstream c-lightning through 0.10.1 allows loss of funds because of dust HTLC exposure.

How urgent is CVE-2021-41592?

Priority 57/100. Critical severity; Remotely exploitable, no login, no user action

References

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