CVE-2020-26896 [High] | Security Vulnerability in Lightning Network Daemon

Prior to 0.11.0-beta, LND (Lightning Network Daemon) had a vulnerability in its invoice database. While claiming on-chain a received HTLC output, it didn't verify that the corresponding outgoing off-chain HTLC was already settled before releasing the preimage. In the case of a hash-and-amount collision with an invoice, the preimage for an expected payment was instead released. A malicious peer could have deliberately intercepted an HTLC intended for the victim node, probed the preimage through a colluding relayed HTLC, and stolen the intercepted HTLC. The impact is a loss of funds in certain situations, and a weakening of the victim's receiver privacy.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-09	0.20%	0.14%	-0.06%
2	2025-11-21	0.14%	0.20%	+0.06%
3	2025-11-18	—	0.14%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-09

0.20%

0.14%

-0.06%

2025-11-21

0.14%

0.20%

+0.06%

2025-11-18

—

0.14%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.2	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	3.9	4.2	[email protected]
5.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:M) Exploitation needs some favorable conditions, but not exceptional ones. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	8.6	4.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

8.2

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

3.9

4.2

[email protected]

5.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:M): Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

8.6

4.9

[email protected]

Affected software / configurations for CVE-2020-26896

Vendor	Product	Version	Raw CPE
lightning_network_daemon_project	lightning_network_daemon	< 0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon::::::::
lightning_network_daemon_project	lightning_network_daemon	0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon:0.11.0:-::::::
lightning_network_daemon_project	lightning_network_daemon	0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon:0.11.0:beta_rc1::::::
lightning_network_daemon_project	lightning_network_daemon	0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon:0.11.0:beta_rc2::::::
lightning_network_daemon_project	lightning_network_daemon	0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon:0.11.0:beta_rc3::::::
lightning_network_daemon_project	lightning_network_daemon	0.11.0	cpe:2.3:a:lightning_network_daemon_project:lightning_network_daemon:0.11.0:beta_rc4::::::

References for CVE-2020-26896

URL	Tags
https://gist.github.com/ariard/6bdeb995565d1cc292753e1ee4ae402d	Third Party Advisory
https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-October/002855.html	Mailing List Third Party Advisory
https://lists.linuxfoundation.org/pipermail/lightning-dev/2020-October/002857.html	Mailing List Patch Third Party Advisory

URL

CVE-2020-26896

Exploit prediction scoring system (EPSS) score for CVE-2020-26896

Common vulnerability scoring system (CVSS) metrics for CVE-2020-26896

Weakness enumeration for CVE-2020-26896

Affected software / configurations for CVE-2020-26896

References for CVE-2020-26896